Mammary-type myofibroblastoma of soft tissue: a tumor closely related to spindle cell lipoma

Mammary myofibroblastoma is a benign breast tumor, with a reported predilection for older men. It is composed of fascicles of spindle cells having features of myofibroblasts, with intervening hyalinized collagenous stroma and a variably prominent component of adipose tissue. The spindle cells characteristically express both CD34 and desmin. Herein, we report the clinicopathologic features of nine tumors that were morphologically and immunohistochemically identical to myofibroblastoma of breast; however, they arose in subcutaneous soft tissue at extramammary sites. The study group comprised seven men and two women with an age range of 35-67 years (median 53 years). Lesions presented as either a slowly growing painless mass or were incidental findings at the time of surgery. The site distribution was as follows: inguinal/groin area (five cases) and one case each in posterior vaginal wall, buttock, anterior abdominal wall, and mid-back. Tumor size ranged from 2 to 13 cm (median 6 cm), and all lesions were well circumscribed. Eight tumors had a component of adipose tissue (ranging from 10% to 60%), within which some variation in adipocyte size was often seen. One case showed epithelioid cytomorphology and three cases showed rare atypical or multinucleated cells. Focal myxoid stromal change was seen in four cases. Tumor cells were positive for desmin (9 of 9 cases), CD34 (8 of 9 cases), and occasionally positive for smooth muscle actin (3 of 9 cases). Lesions were marginally excised with no recurrences to date, although follow-up is very limited. Lesions with morphologic and immunophenotypic features similar to myofibroblastoma of breast can arise at extramammary sites, with an apparent predilection for the inguinal area of older men. Both mammary and extramammary lesions show morphologic overlap with spindle cell lipoma and are likely closely related.     

Intraarticular nodular fasciitis--a rare lesion: clinicopathologic analysis of a series

Nodular fasciitis is a benign myofibroblastic proliferation with a predilection for the subcutaneous tissues of the upper extremities, trunk, and head and neck of young adults. Nodular fasciitis is not generally recognized to arise within joints. In this study, the clinicopathologic and immunohistochemical features of 10 cases of intraarticular nodular fasciitis are described. Six patients were female and 4 were male, with a median age of 33 years (range, 9-50 years). Lesional size ranged from 2 to 4 cm (median, 2.6 cm). Seven tumors arose in the knee, 2 in the hand, and 1 in the ankle. Most patients complained of joint pain; 4 presented with a palpable mass. Only 1 patient reported antecedent trauma. The duration of symptoms prior to surgery ranged from 2 months to 1 year (median, 6 months). The clinical differential diagnoses included giant cell tumor of tendon sheath, pigmented villonodular synovitis, synovial chondromatosis, inflammatory arthritis, and lymphoma. Grossly, the lesions were solid, nodular, rubbery, or firm masses. Histologically, all tumors were circumscribed but unencapsulated and showed typical features of nodular fasciitis, being composed of cytologically bland plump spindle cells arranged in short, intersecting bundles within a variably loose myxoid to collagenous stroma, containing extravasated red blood cells and scattered lymphocytes. Five lesions showed prominent stromal hyalinization, in 2 cases keloidal in appearance. In 4 cases, the tissue at the periphery of the lesion showed hemosiderin deposition. By immunohistochemistry, all tumors examined were positive for SMA, 1 was positive for desmin, and all were negative for caldesmon and S-100 protein; none showed nuclear staining for beta-catenin. Clinical follow-up information was available for 5 patients, ranging from 2 to 86 months. No lesion recurred. In summary, intraarticular nodular fasciitis occurs most commonly in the knees of young adults, and often appears to have a somewhat longer preoperative duration than typical subcutaneous or intramuscular nodular fasciitis. Intraarticular lesions show morphologic features similar to other cases of nodular fasciitis, with the exception that stromal hyalinization and adjacent hemosiderin deposition are common, likely attributable to frictional trauma in this location.     

Deep "benign" fibrous histiocytoma: clinicopathologic analysis of 69 cases of a rare tumor indicating occasional metastatic potential

Benign fibrous histiocytoma (FH) is one of the most common mesenchymal neoplasms of the skin. Several histologic variants of cutaneous FH have been described, some of which also have distinct clinical features including a propensity for local recurrence. Deep benign FH is an uncommon and poorly recognized clinical subtype that arises in subcutaneous or deep soft tissue. Only a single small series of these neoplasms has been published, and their clinical behavior is not well characterized. In this study, we report the clinicopathologic features of 69 deep FH retrieved from our consultation files. The patients included 41 males and 28 females, ranging in age from 6 to 84 years (median, 37 y). The most common anatomic location was the extremities (58%); the remainder arose on the head and neck (22%), trunk (11%), and in the deep soft tissue of the retroperitoneum, mediastinum, or pelvis (9%). All lesions arising in nonvisceral soft tissue were subcutaneous. The tumors ranged from 0.5 to 25 cm in size (median, 3.0 cm) and were well circumscribed grossly and microscopically. All tumors were composed of bland ovoid to spindle cells arranged in a storiform pattern with admixed lymphocytes. Multinucleate giant cells, osteoclastic giant cells, and/or foam cells were present in 59% of cases, whereas the other 41% were cytologically monomorphic, often resembling cellular FH. Other common findings included a hemangiopericytomalike vascular pattern (42%) and stromal hyalinization (39%). Four cases were classified as atypical deep FH due to the presence of scattered markedly pleomorphic spindle cells within an otherwise histologically typical lesion. The median mitotic rate was 3/10 HPF; 10 cases (14%) had >10 mitoses/10 HPF. Necrosis (2 cases) and lymphovascular invasion (1 case) were rare. Immunohistochemistry revealed expression of CD34 in 20/50 cases (40%), smooth muscle actin in 15/40 (38%), and focal desmin in 1/12 (8%). Of the 37 patients for whom clinical follow-up was available (median, 40 mo), 8 (22%) had a local recurrence; in all 8 cases, the tumor had been marginally or incompletely excised. Metastases occurred in 2 patients (5%), both of whom ultimately died of disease; however, this number is likely exaggerated due to consultation bias. The metastasizing tumors were large (6 and 9 cm) and 1 had tumor necrosis but they were otherwise histologically identical to the nonmetastasizing lesions. In summary, deep FH has many histologic features in common with cutaneous cellular FH; however, it usually has a more diffusely storiform pattern than the latter, is well circumscribed, and may have striking hemangiopericytomalike vessels. Similar to the cellular, aneurysmal, and atypical variants of FH, deep FH recurs in approximately 20% of cases and may rarely metastasize.     

Deep-seated plexiform schwannoma: a pathologic study of 16 cases and comparative analysis with the superficial variety

Plexiform schwannoma (PS) is one of the least common histologic variants of schwannoma. It shows a plexiform growth pattern and typically occurs in the dermis and subcutaneous tissue. Morphologically, PS can display a conventional, cellular, or mixed appearance. However, the frequent cellular morphology associated with hyperchromatic nuclei, increased mitoses, and plexiform growth can suggest a malignant process, mainly a high-grade malignant peripheral nerve sheath tumor (MPNST). The purpose of this study was to analyze the clinicopathologic features of deep-seated PS and compare them with the superficial counterparts. Sixteen deep-seated PSs were analyzed clinicopathologically, immunohistochemically, and ultrastructurally, and compared with 8 superficial (5 dermal and 3 subcutaneous) PSs. There were 12 females and 4 males, ranging from 5 months to 61 years of age. Fifteen tumors were located in the deep somatic soft tissue (extremities, 8; retroperitoneum/pelvis, 3; trunk, 2; parotid, 1; vulva, 1) and 1 tumor was located in the thoracic esophagus. None of the patients had stigmata of neurofibromatosis. Local recurrence was noted in half of the patients with clinical information available, but none had evidence of disease at last follow-up. Worrisome morphologic features included: increased cellularity (68%), mild to moderate pleomorphism (50%), and mitotic activity (93%) ranging from 1 to 10 MF/10 high power fields (HPFs). Focal necrosis was seen in 12% and myxoid change was identified in 18% of cases. Immunohistochemical stains for S-100 protein showed strong and diffuse positivity on all cases tested. Ultrastructurally, findings characteristic of schwannian differentiation were identified in the cases analyzed. The 8 superficial PSs showed increased cellularity and mild to moderate pleomorphism in 62% of cases but lacked tumor necrosis. Deep-seated PS is a rare, under-recognized PNST of deep soft tissue, typically not associated with neurofibromatosis. Although commonly occurring in the extremities, they can be seen in other locations including the viscera. In contrast with the more common superficial (dermal and subcutaneous) tumors, deep PSs have a predilection for females, can occur in congenital settings, and can show necrosis and myxoid change. Common worrisome histologic features seen in both groups include increased cellularity and mitoses. It is important to differentiate these tumors from plexiform neurofibromas and MPNSTs as they follow a benign clinical course, with complete surgical excision being curative.     

Microcystic/Reticular Schwannoma Arising in the Submandibular Gland: A Rare Benign Entity that Mimics More Common Salivary Gland Carcinomas

Microcystic/reticular schwannoma is a recently described variant of schwannoma with a predilection for the gastrointestinal tract, rarely involving the head/neck region. This is the first reported case involving the submandibular gland. We present a case in a 34 year old man with 4.5 cm submandibular mass. Fine needle aspiration suggested a spindle cell lesion. Frozen section evaluation raised the possibility of mucoepidermoid carcinoma. Resection showed a well circumscribed mass with a mucoid appearance. Histologic findings include a lobular architecture with fibrous septa, a lympho-plasmacytic infiltrate, and scattered lymphoid aggregates at the periphery. There are two distinct histologic patterns with solid areas of spindle cells and areas of spindle/ovoid cells with a microcystic pattern in a myxoid background. The tumor has a pushing border, with extension into adipose and adjacent parenchyma, without cytologic atypia or necrosis. Immunohistochemical stains are positive for S-100 and CD34, and negative for calponin, mammoglobin, ALK1, p63, ER, GFAP, SMA, desmin, cytokeratin 7, cytokeratin AE1/AE3, and C-Kit. Mucicarmine stain is negative. Recognition of this benign unusual variant of schwannoma is paramount for appropriate conservative treatment due to the morphologic and immunohistochemical overlap with primary salivary gland carcinomas.     

Benign epithelioid peripheral nerve sheath tumors of the soft tissues: clinicopathologic spectrum of 33 cases

Benign epithelioid peripheral nerve sheath tumors (BEPNSTs) have not been fully characterized, and their relationship to conventional schwannoma and neurofibroma has not been satisfactorily established. Herein, we detail the clinicopathologic features of 33 examples of BEPNST. The study included 22 females and 11 males ranging in age from 2 to 68 years (median, 31.5 years). Only one patient probably has neurofibromatosis type 1. The tumors were predominantly dermal/subcutaneous in location (85%) and involved the lower limb (n=15), upper limb (n=11), trunk (n=4), and head/neck (n=3). The lesions ranged in size from 0.3 to 6.8 cm (median, 1.1 cm). Microscopically, the tumors were generally well-circumscribed, uninodular, or multinodular masses. Twenty-six lesions were encapsulated. Tumors consisted of trabeculae, loosely arranged nodules, and cohesive nests of epithelioid tumor cells immersed in collagenous, myxohyaline, or chiefly myxoid stroma. A bland spindled cell component comprising 5% to 40% of the tumor was noted in 15 cases. Mitotic activity ranged from 0 to 6 mitoses/50 high power fields (mean, 1.5 mitoses/50 high power fields) with no abnormal division figures identified. Five lesions were considered atypical based on presence of focal nuclear/nucleolar enlargement and hyperchromasia. Immunohistochemical reactivity for Schwann cell-related markers in tumor cells included S-100 protein (20 of 20 cases), collagen type IV (10 of 10), laminin (8 of 8), nerve growth factor receptor, p75(7 of 8), CD57 (6 of 9), and glial fibrillary acidic protein (8 of 15). CD34-positive fibroblast-like cells were identified in all 12 neoplasms tested. Anti-epithelial membrane antigen highlighted perineurial cells in 9 of the 11 encapsulated tumors. Anti-neurofilament protein did not identify intralesional neuraxons in the 10 tumors evaluated. Eighteen tumors were subtyped as epithelioid neurofibromas. The remaining 15 cases showed some histologic features suggestive of schwannoma, but their uniform cellularity, absence of nuclear palisading, and presence of a significant CD34-positive spindled cell population in 5 cases led to their classification as "BEPNST of indeterminate histogenesis." Evaluation for loss of heterozygosity in 2 cases demonstrated deletion of genetic material on chromosome 22q and 17q involving NF2 and NF1 loci. However, sequencing of NF2 coding sequences revealed no mutations. Follow-up for 18 patients (median interval, 13.5 years), including 4 patients with tumors exhibiting cytologic atypia, revealed a nondestructive recurrence or persistent disease in 3 patients whose tumors lacked atypia, but no evidence of metastatic spread or tumor-related death. BEPNSTs are usually small neoplasms located in superficial soft tissue and have an excellent prognosis after complete local excision. Accurate subclassification of some of these lesions is difficult based on currently available techniques.     

Pseudoglandular schwannoma of the cauda equina. Case report

The authors present a case of pseudoglandular schwannoma with immunohistochemical findings consistent with epithelial metaplasia. Pseudoglandular schwannoma is a rare morphological variant of benign schwannoma characterized by the presence of glandlike structures lined with Schwann cells. To the best of the authors' knowledge, this is only the fifth case of pseudoglandular schwannoma reported in the literature. Clinical, imaging, and pathological findings are described. The pathological findings were consistent with a pseudoglandular schwannoma composed of typical Schwann cells arranged in an Antoni B pattern, with numerous large pseudocystic spaces. Serial immunohistochemical studies of tissue sections revealed that the cells lining the pseudoglandular spaces were not only diffusely reactive for S100 protein, but also demonstrated focal positivity for epithelial membrane antigen and cytokeratins AE and AE3. The particular immunohistochemical features of incompletely differentiated Schwann cells in the present case give support to the metaplastic theory of the origin of glandlike structures in benign peripheral nerve sheath tumors.     

Benign schwannoma of the digestive tract: a clinicopathologic and immunohistochemical study of five cases, including a case of esophageal tumor

We report five cases of schwannomas of the digestive tract. The patients were two men and three women, whose ages ranged from 56 to 74 years. Three cases arose in the stomach, one in the ascending colon, and one in the esophagus; the latter was a hitherto unreported location for this tumor. The schwannomas ranged from 2 to 11 cm in diameter. They were well circumscribed but not encapsulated, with interlacing bundles of spindle cells, nuclear atypia and no mitosis, interspersed with collagenous strands. Inflammatory cells were scattered throughout the tumors and a peripheral cuff of lymphoid aggregates was observed in all cases. Intracellular periodic acid-Schiff (PAS)-positive crystalloids were found in three cases; no skeinoid fibers were seen. A diffuse and intense positivity for vimentin and S-100 protein was detected in all five cases together with a variable and sometimes focal positivity for glial fibrillary acidic protein and neuron-specific enolase. None of the tumors showed expression of CD34 or the smooth muscle antigens tested. The four cases with a sufficient follow-up had a favorable outcome without any recurrence or metastasis. The morphologic and immunohistochemical features of digestive schwannomas were compared with those of other gastrointestinal stromal tumors. Schwannomas have many differences. Digestive schwannomas can be readily recognized on histologic and immunohistochemical examination. They are spindle cell tumors without epithelioid features, with a peripheral cuff of lymphoid tissue. Specific intracellular needle-shaped PAS-positive crystalloids are found in some cases, whereas skeinoid fibers are not. These tumors always express S-100 protein in a diffuse and strong manner, and they express glial fibrillary acidic protein but not express CD34. Digestive schwannomas usually are gastric tumors and have never been reported in the small bowel. They pursue a benign course and are far rarer than gastrointestinal autonomic nerve tumors.     

Extranodal histiocytic sarcoma: clinicopathologic analysis of 14 cases of a rare epithelioid malignancy

Histiocytic sarcoma is a rare malignant neoplasm that occurs in lymph nodes, skin, and the gastrointestinal tract. Many previously published cases were likely misdiagnosed examples of non-Hodgkin lymphoma. Only small numbers of bona fide examples exist in the world literature; cases arising primarily at extranodal sites are not well described and often seem to go unrecognized. To characterize these tumors further, 14 extranodal histiocytic sarcomas were analyzed. Hematoxylin and eosin sections were reexamined, immunohistochemistry was performed, and clinical details were obtained from referring hospitals. Eight patients were female and 6 male (median age, 55 years; range, 15-89 years). All patients presented with a solitary mass, ranging in size from 1.8 to 12 cm (median 6.8 cm). Seven tumors arose in soft tissue (6 lower limb; 1 upper limb), 5 in the gastrointestinal tract (1 involving both stomach and colon, 1 ileum, 2 rectum, 1 anus), 1 in the nasal cavity, and 1 in the lung. Three gastrointestinal tract tumors also involved regional lymph nodes, and 1 involved the liver. Most cases had infiltrative margins. The tumors were generally composed of sheets of large epithelioid cells with abundant eosinophilic cytoplasm, oval to irregular nuclei, vesicular chromatin, and large nucleoli. Binucleated cells were common, and 6 cases contained tumor giant cells. Mitoses ranged from 1 to 64 per 10 HPF (median 11 per 10 HPF). Necrosis was present in 8 cases. Nearly all tumors showed a striking inflammatory infiltrate, most often of neutrophils or lymphocytes. All cases were reactive for LCA, CD45RO, and CD68 (KP1 and PG-M1); 13 of 14 (93%) expressed CD4, 12 of 14 (86%) lysozyme, 8 of 10 (80%) CD31, 7 of 14 (50%) S-100 protein, and 5 of 14 (36%) focal CD1a. Two tumors showed weak, focal cytoplasmic positivity for CD30, and 1 for epithelial membrane antigen. The tumors were negative for ALK-1, CD21, CD35, CD3, CD20, CD34, myeloperoxidase, HMB-45, and keratins. Gastrointestinal tract cases were negative for c-kit and desmin. Six patients were treated with postoperative radiation and 7 with chemotherapy (CHOP or ProMACE-MOPP). Follow-up was available for 10 patients (median, 24 months; range, 4 months to 11 years). Two tumors recurred locally, and 5 patients developed distant spread: 3 to lymph nodes, 1 to lung, and 1 to bone. At the last follow-up, 2 patients have died of disseminated disease, 4 and 5 months following initial diagnosis. The patients who died thus far had the largest primary tumors. Histiocytic sarcoma may arise primarily in soft tissue and shows reproducible histologic features, including abundant eosinophilic cytoplasm and a prominent inflammatory infiltrate. Metastatic carcinoma, metastatic melanoma, and large cell non-Hodgkin lymphomas should be excluded by immunohistochemistry. Histiocytic sarcoma has the potential for an aggressive clinical course, most often with lymph node involvement. However, a subset of cases presenting with clinically localized disease have a favorable long-term outcome. Tumor size may be a prognostic factor.     

Lipoblastic nerve sheath tumors: report of a distinctive variant of neural soft tissue neoplasm with adipocytic differentiation

Benign nerve sheath tumors of soft tissue can occasionally adopt unusual or unfamiliar morphologic appearances that may introduce difficulties for diagnosis, such as multinucleation, bizarre nuclei, intranuclear vacuoles, and other degenerative changes. Tumor cells adopting a signet-ring or lipoblast-like configuration, however, are mostly associated with epithelial malignancies, liposarcoma and melanoma, and have been only rarely observed in spindle cell tumors of soft tissue. We report 5 cases of benign nerve sheath neoplasms that displayed prominent signet-ring cells with lipoblast-like features. The cases presented as solitary soft tissue masses in the groin, thigh, retroperitoneum, and shoulder in 4 men and 1 woman between the ages of 31 to 57 years. Four tumors predominantly showed features of schwannoma and one of neurofibroma; however, intimately admixed with the spindle cell population, there were also numerous scattered mature adipocytes as well as lipoblast-like cells displaying a signet-ring cell appearance. Immunohistochemical studies showed strong S-100 protein positivity in the spindle cells as well as in the signet-ring lipoblast-like cells and the mature adipocytes. The signet-ring cells were negative for mucin stains, cytokeratin, EMA, CEA, and several other differentiation markers. Ultrastructural examination was performed in 2 cases. The signet-ring cells contained large cytoplasmic lipid droplets that displaced the nuclei to the periphery, consistent with lipoblastic differentiation, whereas complex, interdigitating cytoplasmic processes covered by basal lamina material characteristic of nerve sheath differentiation could be identified in the spindle cells. Four patients for whom follow-up was available were alive and well with no evidence of recurrence over a period of 28 to 116 months (median follow-up, 50 months). The presence of mature fat and signet-ring lipoblast-like cells within a nerve sheath neoplasm is quite rare and may signify a process of aberrant differentiation. Neurogenic tumors should be added in the differential diagnosis of spindle cell tumors capable of displaying prominent signet-ring cell features.     

Do leiomyomas of deep soft tissue exist? An analysis of highly differentiated smooth muscle tumors of deep soft tissue supporting two distinct subtypes.

There is a prevailing view that leiomyomas of deep soft tissue are rare or nonexistent, but there are limited data on this subject in the form of large clinical studies with long follow-up information. We reviewed 36 consultation cases that had been diagnosed as leiomyoma or probable leiomyoma based on absence of nuclear atypia, necrosis, and no/minimal mitotic activity. Follow-up information was obtained to determine whether these stringent histologic criteria could identify a biologically benign group of smooth muscle tumors of deep soft tissue. The tumors occurred in two distinct locations. The first (n = 13) occurred in deep somatic soft tissue of the lower extremity (7), upper extremity (2), trunk (2), axilla (1), and back (1) and affected the sexes equally (7 male, 6 female). Composed of a circumscribed mass of mature smooth muscle cells, they were frequently calcified with a mean mitotic activity of <1 mitosis/50 high power fields (HPF) (range 1-4 mitoses/50 HPF). Estrogen receptor and progesterone receptor proteins were negative in the three cases tested. No tumors recurred or metastasized (mean follow-up 58.7 months, range 5-97 months). The second group (n = 23) occurred within the retroperitoneum (20) or abdominal cavity (3) of women (1 male, 22 female). Resembling uterine leiomyomas, they were always distinct from the uterus, occasionally multiple (n = 4), and sometimes occurred up to years after hysterectomy (n = 3). Four cases occurred with synchronous uterine leiomyomas. In the six cases tested, five of six were positive for the estrogen receptor protein and all were positive for progesterone receptor protein. Mean mitotic activity was 1 mitosis/50 HPF (range <1-10 mitoses/50 HPF). None developed metastasis within the follow-up period (mean 42.5 months, range 6-120 months); one tumor with a positive margin recurred at 10 months. We conclude that clinically benign smooth muscle tumors of deep soft tissue are rare but can be identified using stringent histologic criteria. They comprise two distinct subtypes: leiomyomas of somatic soft tissue and retroperitoneal-abdominal leiomyomas. The latter probably arise from hormonally sensitive smooth muscle. Although similar to uterine leiomyomas, they are located at sites removed from the uterus and are likely independent soft tissue primaries rather than parasitic leiomyomas of the uterus. We suggest that these two groups of smooth muscle tumors be diagnostically approached in a site-specific fashion.     

Reticular perineurioma: a distinctive variant of soft tissue perineurioma

Soft tissue perineurioma is a relatively recently characterized, uncommon tumor composed of perineurial cells exhibiting immunoreactivity for epithelial membrane antigen (EMA). These lesions occur preferentially in adults and may arise in a wide variety of anatomic sites. We report the clinicopathologic, immunohistochemical, and ultrastructural features of six cases of a poorly recognized morphologic variant of soft tissue perineurioma, characterized by a highly distinctive reticular growth pattern. Four of the patients were women, two were men (age range, 34-61 yrs; median, 43 yrs). Four of the cases arose in the subcutis of the upper extremity; three were located distally (thumb, finger, palm), whereas one was situated more proximally near the elbow region. One case each was located in the gingiva and subcutaneous tissue of the inguinal region, respectively. In those cases in which clinical information was available (n = 5), the lesions were asymptomatic and had been present from 4 months to 10 years before resection. Tumor size ranged from 1.5 cm to 10 cm (median size, 4.25 cm). Microscopically the lesions demonstrated a predominantly lace-like or reticular growth pattern composed of anastomosing cords of fusiform cells with bipolar cytoplasmic processes and palely eosinophilic cytoplasm. Nuclei were centrally placed, ovoid to fusiform in shape, and no mitoses were seen. Transition to more cellular areas was focally present in all cases. The stroma was variably collagenous to myxoid. Immunohistochemically all six cases stained positively for EMA but not for S-100 protein. Two cases demonstrated focal positive cytoplasmic staining for cytokeratin, whereas one case was focally desmin positive. Ultrastructural examination of two tumors showed typical features of perineurial cells. Follow up (available in only two cases) showed no evidence of recurrence. Reticular perineurioma of soft tissue represents an unusual morphologic variant within the perineurioma group, which should be distinguished from myoepithelial tumors, extraskeletal myxoid chondrosarcoma, and myxoid synovial sarcoma.     

Digital fibromyxoma (superficial acral fibromyxoma): a detailed characterization of 124 cases

Digital fibromyxoma (first described by Fetsch and colleagues as superficial acral fibromyxoma) is a distinctive soft tissue tumor with a predilection for the subungual or periungual region of the hands and feet. This report details the histologic, immunophenotypic, and clinical findings in 124 cases of digital fibromyxoma. The study group included 70 male and 54 female patients (1.3:1, M:F), ranging in age from 4 to 86 years (mean, 48 y; median, 49 y). Mean tumor size was 1.7 cm (range, 0.5 to 5 cm; median, 1.5 cm). Nearly half of the patients (41%) presented with a painful mass. Tumors arose on the hands (52%) or feet (45%), with rare tumors arising on the ankle or leg. Most tumors occurred on the digits (94% of hand tumors, 82% of foot tumors), with the majority growing in close proximity to the nail (97% on fingers, 96% on toes). Histologically, 80% of cases were poorly marginated; 70% infiltrated the dermal collagen, 27% infiltrated fat, and 3% invaded bone. In cases in which imaging studies were available, bone involvement by an erosive or lytic lesion was more frequent (9/25, 36%). All tumors were composed of spindle-shaped or stellate-shaped cells with palely eosinophilic cytoplasm and a random or loosely fascicular growth pattern. The tumor cells were separated by dense hyaline collagen alternating with myxoid stroma. Most (86%) of the tumors showed alternating areas of fibrous and myxoid stroma, 11% showed predominantly fibrous stroma, and 3% had predominantly myxoid stroma. Increased mast cells were noted in 88% of tumors. All tumors comprised cells with minimal atypia, occasionally showing scattered larger cells with so-called "degenerative change." Mitotic figures were infrequent, and all tumors lacked necrosis, pleomorphism, or neural/perineural infiltration. Multinucleate stromal cells were occasionally seen. Tumor cells were reactive for CD34 in 42/61 cases (69%), with rare tumors showing focal reactivity for EMA (3/40, 7.5%), smooth muscle actin (5/42, 12%), and desmin (1/18, 6%). All tumors were negative for S100 (0/66), MUC4 (0/11), GFAP (0/10), AE1/AE3 (0/4), Cam5.2 (0/2), PanK (0/2), Claudin (0/4), and NFP (0/3). Follow-up in 47 cases ranged from 1 to 252 months (mean, 35 mo). Ten tumors (24%) recurred locally (all near the nail unit of the fingers or toes) after a mean interval of 27 months. One tumor recurred twice. All recurrent tumors had positive margins on initial biopsy or subsequent excision and no other clinical or pathologic features correlated with recurrence/persistence. To date, no tumor has metastasized. Finally, sequencing of 8 digital fibromyxomas failed to reveal mutations in exon 8 or 9 of GNAS1, in contrast to intramuscular or cellular myxoma.     

腹内胃肠外间质瘤30例临床病理分析

目的研究腹内胃肠外间质瘤(EGIST)临床病理特点及预后。方法复阅1986年7月至2003年6月47例经病理诊断为腹腔或腹膜后平滑肌瘤、平滑肌肉瘤、平滑肌母细胞瘤、许旺细胞瘤和间质瘤患者的组织切片,重新诊断,免疫组织化学染色检测CD117、CD34、SMA、Desmin及S-100 5种蛋白表达,分析其临床病理变量与预后的关系。结果30例患者最终确诊为EGIST。肿瘤位于肠系膜12例,腹膜后8例,小网膜囊6例,其余4例肿瘤病例记载为腹腔来源。肿瘤中位直径12.5(4～30)cm,其中梭形细胞为主型23例,上皮为主型4例,混合型3例。随访中位时间44个月。随访率90%。全组患者1、3、5年生存率分别为79.7%、59.5%和45.4%。单因素分析结果显示.肿瘤位于腹膜后和肠系膜及腹腔、肿瘤直径超过10cm、肿瘤有坏死、核分裂像数目超过5个/ 50HPF、肿瘤细胞异型性和中、低分化的肿瘤,其预后不佳。结论EGIST有其特有行为谱,预后评价除参照GIST的指标外;肿瘤直径超过10cm和肿瘤的生长部位有助于对EGIST预后的判断。     

Malignant Sertoli cell tumors of the testis: a study of 13 examples of a neoplasm frequently misinterpreted as seminoma

The distinction of Sertoli cell tumors from seminoma is critical to ensure proper treatment. Although usually straightforward, we highlight herein 13 malignant Sertoli cell tumors of the testis with light microscopic features that mimicked seminoma. All of the cases were received in consultation, 10 with submitting diagnoses of seminoma, usually of classic type, but three cases of spermatocytic type. Patients ranged from 15 to 80 years of age (median 37 years); all presented with testicular masses. The tumors were typically firm, white to yellow-tan, and often had foci of hemorrhage. The dominant microscopic pattern was nested or sheet-like, with some tumors having secondary patterns of trabeculae-solid tubules, hollow tubules, and pseudofollicles. Tumor cells were polygonal with conspicuous clear cytoplasm in 12 cases; the cytoplasm was focally eosinophilic in 10 cases, but this was never conspicuous. Nine tumors had cytoplasmic vacuoles, and three of four that were investigated stained for intracytoplasmic glycogen. Nuclei were small (5) to medium-sized (8), round-to-oval (13), and vesicular with irregular contours (11). Nucleoli were present in 11 tumors (six small; five large). Stromal fibrosis (12) and lymphoid infiltrates (10) were conspicuous, and tumor necrosis (11) and vascular invasion (8) also were seen. Mitotic figures ranged from <1 to 21/10 high power fields (HPF) (median 1/10 HPF). Staining for inhibin-alpha, epithelial membrane antigen, and cytokeratin (AE1/AE3) was positive in four of four, six of six, and three of six cases, respectively; placental alkaline phosphatase was negative in all five tumors investigated. The nested growth pattern, prominence of clear cells, lymphoid infiltrate, inconspicuous tubular differentiation, cytoplasmic glycogen, and prominent nucleoli caused these tumors to be mistaken for seminomas. The smaller, less pleomorphic nuclei of Sertoli cell tumors, their lower mitotic rate, and the absence of intratubular germ cell neoplasia are helpful differential features. Immunohistochemistry is a useful adjunct in confirming the diagnosis of Sertoli cell tumor, but only if the overlapping features are appreciated by conventional microscopy and the diagnosis of Sertoli cell tumor included in the differential.     

Pseudomyogenic hemangioendothelioma: a distinctive, often multicentric tumor with indolent behavior

A 1992 report described 5 keratin-positive spindle cell neoplasms with multifocal presentation in a single limb, which were proposed at that time to be a variant of epithelioid sarcoma. This tumor type is not widely recognized and is incompletely characterized. We examined 50 cases of this distinctive tumor to evaluate histologic, immunophenotypic, and clinical features. There was a 4.6:1 male predominance (mean age, 31 y; 82% ≤40 y). Half of the patients presented with painful nodules and the other half with painless nodules. Mean tumor size was 1.9 cm (range, 0.3 to 5.5 cm). Tumors arose in the lower limb (54%), the upper limb (24%), trunk (18%), or head and neck (4%). Thirty-three (66%) were multifocal lesions (ranging from 2 to 15 lesions), including 32 cases with involvement of multiple tissue planes. Of 205 total lesions, 64 (31%) involved the dermis, 42 (20%) involved the subcutis, 70 (34%) lesions involved muscle, and 29 (14%) lesions involved bone; all the lesions had infiltrative margins. The tumors were composed of loose fascicles and sheets of plump spindle cells with vesicular nuclei, variably prominent nucleoli, and abundant brightly eosinophilic cytoplasm, some with a strikingly rhabdomyoblast-like appearance. In all cases, a minority of cells were epithelioid. Twenty-seven tumors contained a prominent neutrophilic inflammatory infiltrate. Most tumors showed only mild nuclear atypia; 6 tumors contained foci of notably pleomorphic cells. The median mitotic rate was 1 per 10 HPF (range, 1 to 10). Seven tumors showed vascular invasion; 7 tumors had areas of necrosis. By immunohistochemistry, all tumors were diffusely positive for AE1/AE3 and FLI1; 22 of 47 tumors were variably positive for CD31. Focal positivity was seen for CAM5.2 (21 of 35), smooth muscle actin (14 of 42), epithelial membrane antigen (7 of 49 weak), and PAN-K (MNF116) (1 of 47). All were negative for CD34, desmin, and S100 protein and showed intact INI1 expression. Follow-up was available for 31 patients and ranged from 9 months to 17 years (mean, 4 y). Most lesions were treated by local excision. Eighteen (58%) patients had local recurrence or developed additional nodules in the same region, all but one, within 1 year of first presentation. Eight patients had postoperative radiation therapy and 6 patients had chemotherapy. Four patients had amputations for multifocal disease. One patient had a regional lymph node metastasis, and, thus far, only 1 patient has developed distant metastases (disseminated), 16 years after primary tumor excision. At the time of the last follow-up, 27 patients were alive with no evidence of the disease, 1 patient was alive with unknown disease status, 2 patients were alive with recurrent disease, and 1 patient died of the disease. In summary, we describe a distinctive type of rarely metastasizing ("intermediate") tumor affecting mainly young men and usually characterized by multifocality in different tissue planes of a limb. Although sharing some features with epithelioid sarcoma (skin/soft tissue of distal extremities, young adults, keratin positive), it differs by having predominantly myoid-appearing spindle cell morphology, expression of FLI1, common reactivity for CD31, lack of epithelial membrane antigen, CD34, and PAN-K expression, and intact INI1. The overall immunophenotypic findings favor endothelial differentiation. Despite the ominous presentation, follow-up thus far suggests an indolent clinical course with a small risk of distant metastasis. Although the precise nosologic status of this tumor type is uncertain, we propose the interim designation "pseudomyogenic hemangioendothelioma."     

Smooth muscle neoplasms of the urinary bladder: a clinicopathologic comparison of leiomyoma and leiomyosarcoma

We report the clinicopathologic, immunohistochemical, and DNA ploidy findings of 18 leiomyosarcomas of the urinary bladder. In addition, we compare these malignant smooth muscle tumors with 10 cases of urinary bladder leiomyoma. The 14 male and four female patients with leiomyosarcoma ranged in age from 25 to 88 years (mean 64 years). The tumors ranged from 3.0 to 15.0 cm (mean 7.1 cm) in greatest dimension and were moderately to highly cellular, consisting of interlacing fascicles of spindled cells with mild to marked nuclear atypia. Coagulative tumor necrosis was identified in 14 cases (78%), and mitotic activity ranged from 1 to 42 mitotic figures (MF) per 10 high power fields (HPF) (mean 12 MF/10 HPF). Tumors were classified as either high-grade (12 cases) or low-grade (six cases) based on nuclear atypia, mitotic activity, and tumor necrosis. Actin positivity was present in 15 tumors (83%), and desmin immunoreactivity was present in seven tumors (39%). All cases were negative for epithelial markers and S-100. Proliferative activity, as assessed by MIB-1 staining, ranged from 0.1% to 51.4% (median 9.1%). Seven (39%) of the leiomyosarcomas were DNA aneuploid, eight (44%) were tetraploid, and three (17%) were diploid. Five patients underwent radical cystoprostatectomy, one radical cystectomy, seven had partial cystectomy, two underwent pelvic exenteration, and three patients had transurethral resection only. Follow-up information was available on all 18 cases and ranged from 2 to 68 months (mean 22 months). Of the 12 patients with high-grade tumors, six (50%) died of disease from 2 to 20 months (mean 7 months) after diagnosis and three patients (25%) are alive with metastatic tumor. Two of the six patients with low-grade leiomyosarcoma died of tumor, 61 and 68 months after diagnosis. There were five male and five female patients with leiomyoma ranging in age from 22 to 78 years (mean 61 years). The tumors ranged from 0.5 to 4.5 cm (mean 1.6 cm) in greatest dimension, were well circumscribed, and had low cellularity. Mitotic activity, necrosis, and cellular atypia were absent, and the tumors were strongly positive for both actin and desmin. MIB-1 staining ranged from 0% to 3.8% (median 0.8%). Seven (87.5%) of the leiomyomas were DNA diploid or near-diploid and one (12.5%) was DNA aneuploid. Six patients were treated with transurethral resection and four with partial cystectomy. All 10 patients were alive at the last follow-up (mean follow-up 75 months), and no tumor recurred or metastasized. Our study shows that low-grade leiomyosarcomas are capable of malignant behavior, and high-grade leiomyosarcomas appear to behave more aggressively than low-grade tumors. In addition, the diagnosis of urinary bladder leiomyoma should be reserved for noninfiltrative smooth muscle tumors lacking mitotic activity, cytologic atypia, and necrosis.     

Sclerosing paraganglioma: report of 19 cases of an unusual variant of neuroendocrine tumor that may be mistaken for an aggressive malignant neoplasm

Nineteen cases of a distinctive variant of paraganglioma characterized by extensive collagen deposition resulting in a pattern of growth that resembled an invasive malignant neoplasm are described. The patients were 3 men and 16 women, 32 to 69 years of age (mean, 50.5 years). The tumors were located in the carotid body region, parapharyngeal region, and mediastinum. Tumor size ranged from 2 to 6 cm in greatest diameter. Grossly, the tumors were described as rubbery to firm, tan-red, and with extensive areas of sclerosis. Histologic examination showed nests and cords of tumor cells separated by broad bands of fibrous tissue. The tumor cells ranged from round to polygonal with abundant cytoplasm to elongated spindle cells with scant cytoplasm. Nuclear cytomegaly was present focally enhancing the atypical appearance of the tumor cell population in 17 cases. Mitoses were sparse (<1 x 10 HPF), and there was no evidence of necrosis in any of the cases. Foci of vascular and perineural invasion were present in 2 and 4 cases, respectively. The most striking morphologic feature was the presence of irregular cords and bands of hyalinized fibrous tissue that compartmentalized the lesion into irregular nests, islands, or cords of tumor cells, imparting them with an infiltrative appearance. All the tumors showed positive immunostaining for chromogranin, synaptophysin, and monoclonal neuron specific enolase. S-100 protein stains identified a sustentacular cell network, whereas cytokeratin AE1/AE3 was negative in all cases. Clinical follow-up in 14 cases, ranging from 2 months to 20 years (mean follow-up, 6.6 years) showed evidence of local recurrence in 2 cases and the development of a separate tumor in the contralateral neck in 1 case. The remainder of patients were free of recurrence or metastasis following simple local excision. Because of the prominent sclerosis, a diagnosis of an invasive malignant neoplasm was initially considered in the majority of cases. Sclerosing paraganglioma should be included in the differential diagnosis of sclerosing lesions of the head and neck region and mediastinum. Appropriate immunohistochemical stains may be of aid for establishing the correct diagnosis.