Myxoid dermatofibroma on a great toe: a case report

Dermatofibroma is a common benign fibrohistiocytic tumor with many clinicopathological variants. Myxoid dermatofibroma is one of these variants, which is characterized by marked stromal mucin deposition. This report presents a case of myxoid dermatofibroma on a great toe that had been slowly growing for two years. Histopathologically, the relatively well-circumscribed dermal tumor was separated from the epidermis by a small grenz zone. The tumor tissue consisted of oval to spindle-shaped cells with well-defined cell borders and spindly condensed nuclei. No cytologic atypia or mitotic figures were found. Although most of the tumor cells were embedded in a prominently myxoid stroma, typical features of classic dermatofibroma including a storiform growth pattern and more densely packed collagen were observed at the periphery. Immunohistochemically, the tumor cells showed positive staining for CD68 and CD99, and negative staining for CD34 and S-100. Histopathological differential diagnoses of myxoid dermatofibroma include soft tissue neoplasms with myxoid tumor stroma, such as superficial acral fibromyxoma, cellular digital fibroma, superficial angiomyxoma, myxoid dermatofibrosarcoma protuberans and low-grade fibromyxoid sarcoma. Immunohistochemical staining can be useful in the differential diagnosis of these tumors. This case highlights the challenges encountered in the histopathological interpretation of myxoid dermatofibroma. Pathologists should keep in mind the diagnosis of myxoid dermatofibroma when dealing with myxoid neoplastic lesions arising on acral sites.     

Well‐differentiated and dedifferentiated liposarcomas with prominent myxoid stroma: analysis of 56 cases

Aims: Occasional cases of well‐differentiated and dedifferentiated liposarcoma (LPS) contain myxoid stroma, leading to confusion with other sarcomas. The aim of this study was to analyse the clinicopathological and genetic features of well‐differentiated/dedifferentiated LPS with prominent myxoid stroma. Methods and results: Fifty‐six cases of LPS (22 well‐differentiated; 34 dedifferentiated) with prominent myxoid stroma were evaluated. Most arose in the retroperitoneum, abdominal cavity, or spermatic cord. The mean size was 170 mm. Myxoid LPS‐like plexiform vessels were conspicuous in 11 cases of well‐differentiated LPS. In 22 cases of dedifferentiated LPS, myxofibrosarcoma‐like curvilinear vessels were prominent. In other cases, the myxoid component had variably bland or pleomorphic morphology. By immunohistochemistry, staining for MDM2 was positive in 95% of cases, and CDK4 in 78%. Cytogenetics in 13 cases showed ring and giant marker chromosomes. Fluorescence in‐situ hybridization showed amplification of 12q13–15 in six cases evaluated. Of 30 patients with follow‐up, all but one had local recurrences (up to four), but only one has so far had distant metastases. Conclusions: Well‐differentiated/dedifferentiated LPS with prominent myxoid stroma can closely resemble other sarcoma types, especially myxoid LPS and myxofibrosarcoma. The clinical presentation (large retroperitoneal or abdominal tumour) is a clue to the correct diagnosis; the degree of nuclear atypia helps to exclude myxoid LPS. Immunohistochemistry for MDM2 and CDK4 and genetic analysis can be useful to confirm the diagnosis.     

Squamous cell carcinoma with prominent myxoid stroma

Three cases of a squamous cell carcinoma with a prominent myxoid stroma are reported. One case in a 70-year-old woman had presented as a lump in the breast, the other two presented as polypoid lesions of the larynx and cervix uteri in a 65-year-old man and 61-year-old woman, respectively. The carcinomatous component was immersed in abundant extracellular mucosubstances. In addition to occasional squamous pearls, it displayed immunocytochemical evidence of high-weight keratin present in the neoplastic cells and, in one case, desmosomal attachment under electron microscopy. The extracellular mucosubstances proved to be similar to those seen in connective tissue. The differential diagnosis with histologically similar lesions has been taken into consideration, and it has been suggested that this newly described entity showing abundant myxoid stroma has to be distinguished from numerous benign and malignant myxoid soft tissue tumors.     

浅表肢端纤维黏液瘤的临床病理特征

目的 探讨浅表肢端纤维黏液瘤(SAF)的临床病理学特点、免疫表型和鉴别诊断.方法 对1例发生于左手中指末端SAF的临床表现、组织形态和免疫学表型进行回顾性分析,并复习文献.结果 患者男,62岁.因左手中指背侧末端肿块伴疼痛就诊,曾有外伤史.术中见肿块近甲床,并深达骨膜.大体观察,肿块周界不清,直径约2 cm,切面呈灰白色,实性,质韧.镜下观察,肿瘤位于真皮层内,略呈分叶状.瘤细胞由梭形至星形纤维母细胞样细胞组成,呈杂乱状分布于黏液样基质内,局部区域可呈条束状或疏松的席纹状排列.黏液样基质内含有丰富的纤细血管,并可见较多散在的肥大细胞.瘤细胞异型性不明显或仅显示轻度的异型性,核分裂象罕见.肿瘤内也未见坏死.免疫组织化学标记显示,梭形和星形细胞表达波形蛋白、CD34和CD99,灶性表达CD10,不表达上皮细胞膜抗原、肌动蛋白、结蛋白和S-100蛋白.结论 SAF好发于成年人指趾末端.熟悉其临床病理特点则有助于与其他发生于指趾的软组织黏液性肿瘤相鉴别.临床上宜将SAF作完整性切除,以预防局部复发.     

Ossifying fibromyxoid tumor may express CD56 and CD99: a case report

Ossifying fibromyxoid tumor (OFMT) is an uncommon soft tissue neoplasm characterized by a combination of myxoid and/or fibrous stroma with areas of ossification. Although most authors postulate a neuroectodermal origin for this peculiar tumor, there is no agreement in the literature regarding its histogenesis. In this article, we present the immunohistochemical findings of a case of a 39-year-old white male with an OFMT of the soft tissue in the mandibular region. The tumor was positive to S-100 protein, glial fibrillary acidic protein, CD99, CD56 and negative to smooth muscle actin, cytokeratins AE1/AE3, epithelial membrane antigen, and CD68. To the best of our knowledge, this is the first case reported to be positive to CD56 and CD99. Immunoreactivity to these two antibodies, together with reactivity for S-100 protein and glial fibrillary acidic protein, suggests that OFMT is of a neuroectodermal origin. In our opinion, in the absence of reactivity to at least one neuroectodermal marker one should seriously question a diagnosis of OFMT.     

The cytopathology of soft tissue mxyomas: ganglia, juxta-articular myxoid lesions, and intramuscular myxoma

We studied the practicality of issuing a cytologic diagnosis of myxoma/juxta-articular myxoid lesion/ganglion (MJG) by reviewing all fine-needle aspiration (FNA) biopsy specimens of soft tissue masses in our files with diagnoses of myxoma, myxoid cyst, myxoid lesion, ganglion, or ganglion cyst. The control group was soft tissue aspirates with abundant myxoid stroma. Of 39 cases with a cytologic diagnosis of soft tissue MJG, 15 had subsequent tissue biopsy or complete resection of the mass; 24 had clinicoradiologic follow-up. All cases except 1 (fat necrosis) were diagnosed correctly as benign myxoid lesions. We grouped MJG aspirates into 3 subtypes based on clinicoradiologic features: soft tissue ganglion/ganglion cyst (12 cases), juxta-articular myxoid lesion (16 cases), and intramuscular myxoma (11 cases). MJG aspirates showed few, subtle cytopathologic differences among subtypes. They characteristically had a viscous, gelatinous quality when expressed from the needle onto the glass slide. The typical smear contained a film of paucicellular, often finely granular, myxoid stroma, that contained few cells, usually macrophages or bland spindle cells. Control group aspirates always contained cellular components that allowed distinction from MJGs. The cytopathologic diagnosis of MJG lesions is accurate; FNA biopsy can be used to subtype MJGs into 3 categories when clinicoradiologic features are known.     

浅表性血管黏液瘤3例临床病理分析

目的探讨浅表性血管黏液瘤(superficial angiomyxoma,SA)的临床病理特征、免疫组化及鉴别诊断要点。方法对3例SA进行临床病理学及免疫组化染色观察,结合文献对该肿瘤的临床表现、病理形态学特征以及鉴别诊断要点进行讨论。结果 SA主要位于皮肤真皮及皮下,镜下肿瘤略呈分叶状,黏液性基质中可见散在无异型的梭形和星形瘤细胞及较多的中、小薄壁血管,散在有多少不等的中性粒细胞浸润。免疫组化染色显示肿瘤细胞表达vimentin。结论 SA是罕见的黏液性肿瘤,位于皮肤表浅部位,可局部复发但不转移,诊断时应注意和其它黏液性软组织肿瘤鉴别。     

Soft tissue myoepithelioma,a rare tumor. A case report

Myoepithelioma of soft tissues is a rare and under-recognized tumor. We report a case of a myoepithelioma arising in the soft tissue of the wrist in a 37-year-old man. This 3cm, nodular, well circumscribed tumor consisted of a mixture of spindle and epithelioid cells in a fibrous or focally myxoid stroma. Nuclear atypia were mild and mitotic activity was 1 mitotic figure per 10 high-power fields. No tubular epithelial structure was found. The tumoral cells expressed cytokeratin (KL1) and S-100 protein. Smooth muscle actin and desmin were negative. The excision was complete. At 5 months, no recurrence was noted. Myoepithelioma of deep soft tissue has a predilection for extremity involvement. It has to be differentiated from extraskeletal myxoid chondrosarcoma, parachordoma and synovial sarcoma. Most of myoepitheliomas are benign. However, metastasis may occur in a minority of cases.     

Paragastric paraganglioma: a case report with unusual alveolar pattern and myxoid component

Paragangliomas are neural crest-derived neuroendocrine tumors. Nearly 5 to 10% occur in extraadrenal sites, from the upper cervical region to the pelvis, related to the autonomic nervous system. Very few cases of gastric or paragastric paragangliomas have been reported. We report a paraganglioma attached to the stomach of an 85-year-old man. The tumor was 15 cm in diameter and was surgically resected via a subtotal gastrectomy. Fine-needle aspiration smears showed round epithelioid cells forming acini and spindle cells attached to capillaries. Occasional cells showed excentric nuclei and pale vesicular cytoplasm. Microscopically, the tumor was characterized by an alveolar and solid pattern of growth with some unusual features, such as myxoid stroma and pseudoalveoli that contained myxoid material. Spindle cells stained with vimentin and S-100 protein, whereas epithelioid cells showed diffuse cytoplasmic staining with chromogranin A. Electron microscopy of the tumor tissue revealed the presence of neurosecretory granules. To the best of our knowledge, this pattern of growth has yet to be described in the literature and may result in a misdiagnosis if sufficient immunohistochemical markers are not employed. We briefly discuss the cytomorphological features and differential diagnosis of this tumor, which was discovered in a rare location.     

Myxoid melanoma of the skin

We report a case of cutaneous myxoid melanoma in a 61-year-old man. Histologically, the tumor, which showed an adjacent intraepidermal proliferation of atypical melanocytes, was composed of spindle-shaped and epithelioid cells with atypical nuclei, arranged in lobules and embedded in a prominent myxoid stroma. Primary cutaneous myxoid melanoma is rare: we found only one other example in the literature.     

炎性肌纤维母细胞肿瘤临床病理学分析

目的探讨炎性肌纤维母细胞肿瘤(inflammatory myofibroblastic tumor,IMT)的临床病理学特征、诊断与鉴别诊断要点。方法收集江苏省人民医院病理科2010年5月至2020年5月诊治的32例IMT,观察其临床及组织病理学、免疫组织化学及分子病理特点,并复习相关文献。结果患者男19例,女13例,年龄5~65岁(平均年龄37岁)。肺及纵隔10例,胃肠道、肠系膜/大网膜12例,膀胱5例,头颈部3例,小腿软组织及腹膜后各1例,其中4例为上皮样炎性肌纤维母细胞肉瘤(epithelioid inflammatory myofibroblastic sarcoma,EIMS),均位于腹腔。组织学肿瘤以梭形肌纤维母细胞及纤维母细胞增生为主,间质不同程度疏松水肿黏液变至胶原化,伴多少不等的慢性及急性炎性细胞浸润;EIMS以上皮样瘤细胞为主,间质水肿黏液变,浸润炎性细胞主要为中性粒细胞。免疫组织化学:肿瘤细胞表达间变性淋巴瘤激酶(ALK,25/32,78%),除4例EIMS均为核膜阳性外,其余IMT均为胞质阳性;肿瘤细胞还表达广谱细胞角蛋白(8/19)、平滑肌肌动蛋白(24/32,75%)、结蛋白(12/32,38%),其中4例EIMS均为结蛋白强阳性。15例行ALK荧光原位杂交检测显示12例(12/15)可见分离信号,以非经典断裂信号为主。3例行二代测序显示1例小腿IMT出现CLIP2-ALK融合,2例EIMS均示RANBP2-ALK融合。随访29例,22例无瘤生存,4例复发(其中3例克唑替尼治疗并带瘤生存),3例死亡(其中2例为EIMS)。结论IMT形态学谱系广泛,需与多种良恶性肿瘤鉴别,免疫组织化学(抗体ALKp80、ALKD5F3)及荧光原位杂交检测(ALK断裂探针)可辅助IMT的诊断,不典型病例推荐二代测序检测。     

Basal cell adenocarcinoma arising from the minor salivary gland in the soft palate: a case report

Basal cell adenocarcinomas (BCACs) of the oral minor salivary gland are very rare neoplasms. We report on an 86-year-old woman with BCAC arising from the minor salivary gland in the soft palate. Histologically, the tumor was located in the submucosa and showed microinvasion into the adjacent soft tissue without encapsulation. It contained tiny tumor islands with solid and tubular patterns, as well as myxoid stroma. The neoplastic cells were basaloid cells and were composed of large pale cells and small dark cells. They were positive for alpha-smooth muscle actin, cytokeratin 14, and vimentin in the periphery of the tumor island, showing a myoepithelial differentiation. The myxoid stroma was positive for alcian blue and colloidal iron. Apical membranes of the neoplastic cells were positive for MUC1 and CEA. The present case is the 14th documented case of oral BCAC (the fifth case of palatal BCAC).     

Inflammatory myofibroblastic tumor of the perirenal soft tissue misdiagnosed as renal cell carcinoma

Inflammatory myofibroblastic tumor (IMT) of the kidney or perirenal soft tissue is a rare benign lesion that can mimic a malignant renal neoplasm. We describe the case of a 51-year-old woman that had originally been misdiagnosed as renal cell carcinoma in another hospital. Histologic re-evaluation of the tumor in our institution showed that it was in fact an IMT. Awareness of this entity is required for rendering the accurate diagnosis. An association with inflammatory infiltrate, frequent erythrocyte extravasations, edematous or myxoid stroma, absence of atypical mitosis, and the results of a detailed immunohistochemical panel might help in the differential diagnosis. Our patient is recurrence-free in the 18th month of post-operative follow-up.     

Myxoid Variant of Epithelioid Leiomyosarcoma of the Uterus

A rare case of myxoid variant of epithelioid leiomyosarcoma of the uterus in a 76-year-old woman is reported. Palpation and computed tomography revealed an enlarged uterus. Total hysterectomy and bilateral salpingo-oophorectomy were performed, and a hemispheric tumor, measuring 2.7 X 2.5 X 1.8 cm, was found protruding into the uterine cavity of the upper uterine segment. The tumor contained a prominent myxoid stroma and epithelioid tumor cells, which were round and polygonal in shape and showed positive immunoreactivity for desmin and vimentin. High mitotic activity was observed in the tumor cells. Electron microscopic examination revealed bundles of filaments in the cytoplasm and fine reticular material in the extracellular matrix. Histochemically, the myxoid stroma contained abundant acid mucopolysaccharide. The tumor cells were considered to originate from smooth muscle cells, while the myxoid stroma expressed varying differentiation of uterine mesenchymal cells. The patient is currently well with no evidence of recurrence or metastasis one year after the operation. Acta Pathol Jpn 41: 778-783, 1991.     

MALIGNANT FIBROUS HISTIOCYTOMA WITH GRANULAR CELLS, MIMICKING A GRANULAR CELL TUMOR: Light, Electron Microscopic and Immunohistochemical Observation of a Case

The tumor that occurred subcutaneously in the left hypochondriac region of an 87-year-old female is reported. Light microscopically, this tumor was composed of two kinds of cells, spindle cells and granular cells. The spindle cells showed various pictures such as fascicular arrangement, pleomorphic giant cells in the myxoid stroma and areas with abundant blood vessels. The granular cells contained PAS positive and diastase-resistant granules, and these granules, being electron microscopically phagocytic lysosomes, showed the same findings as the granules seen in the granular cell tumor. The immunohistochemical studies for S-100 protein, neuron specific enolase, CEA, myoglobin, and lysosome were negative, but α-antichymotrypsin was positive. From the microscopic and immunohistochemical findings, this tumor was diagnosed as a malignant fibrous histiocytoma with granular cell changes of tumor cells. ACTA PATHOL. JPN. 35 : 1555–1560, 1985.     

Myxoid epithelioid sarcoma: a diagnostic challenge. A report on six cases

Flucke U, Hulsebos T J M, van Krieken J H J M & Mentzel T
(2010) Histopathology 57 , 753–759
Myxoid epithelioid sarcoma: a diagnostic challenge. A report on six cases Aims: Epithelioid sarcoma (ES) is a distinct sarcoma‐type with a specific morphology and immunophenotype. Whereas focal myxoid change does occur, to our knowledge only two cases of ES with diffuse myxoid stroma have been reported previously. To characterize more clearly the myxoid variant of ES, we describe six additional cases and discuss the differential diagnoses. Methods and results: Cases were retrieved from the authors’ files and studied histologically, immunohistochemically and by molecular methods. The age of the patients, four females and two males, ranged from 16 to 74 years (median: 33 years). The neoplasms arose in an extremity (two cases), the abdominal wall, groin, perineum and shoulder (one case each). Histologically, four cases were of the conventional type, and two were of the proximal type and the immunophenotype was typical for ES. The tumour stroma, however, revealed prominent myxoid changes, ranging from 50 to 90% (median: 75%). Only one of the proximal type ES showed a SMARCB1 mutation, whereas the other tumours showed no mutation. Conclusions: The myxoid variant of ES represents a diagnostic challenge and may be confused with other benign and malignant myxoid neoplasms. The main differential diagnosis is myoepithelioma of the skin and soft tissue.     

Myxoid leiomyosarcoma of the liver

This is the first report of a myxoid leiomyosarcoma arising in a cirrhotic liver. The tumor was resected from a 64-year-old man. On gross examination, it was soft and hemorrhagic. The tumor was composed of deceptively benign-looking smooth muscle cells with clear cytoplasm suspended in a myxoid stroma with foci of hemorrhage. Immunohistochemistry and electron microscopy confirmed that this was a smooth muscle cell neoplasm. The abundance of glycogen and ultrastructural signs of smooth muscle differentiation were considered consistent with an immature smooth muscle cell phenotype consistent with the diagnosis of myxoid leiomyosarcoma. Since myxoid leiomyosarcomas are aggressive tumors, it is important to recognize them histologically and also bear in mind that these tumors can occur even in unusual extrauterine locations such as a cirrhotic liver.     

Dendritic fibromyxolipoma on the nasal tip in an old patient

Dendritic myxofibrolipoma is a newly described benign soft tissue tumor that could be easily mistaken for sarcoma. It develops primarily in the subcutis or muscular fascia of the head and neck, shoulders, etc. Histologically, the tumor is characterized by an admixture of mature adipose tissue, spindle and stellate cells, and abundant myxoid stroma with prominent collagenization. These neoplasms typically show positive immunoreactivity for CD-34, vimentin and Bcl-2. Herein, we described a rare case presenting with a papule on the nasal tip in a 69-year old patient. Histopathology and immunohistochemical staining confirmed the diagnosis. In short, it brings the attention of clinicians to the importance of proper identification and characterization of this tumor.     

Epithelial marker-negative desmoplastic small round cell tumor with atypical morphology: definitive classification by fluorescence in situ hybridization

Desmoplastic small round cell tumor typically presents with abundant desmoplastic stroma containing nested primitive round cells bearing a polyphenotypic immunohistochemical profile. Lesions with minimal classic morphology pose a formidable diagnostic challenge. The current case represents one such example, arising as a large abdominal-pelvic mass in a 17-year-old female patient. The tumor was composed of a monomorphous population of small round cells lining microcystic structures and forming pseudoacini and fine anastomosing trabeculae and cords. The stroma was abundantly myxoid with only occasional thick desmoplastic septa. The tumor cells were variably immunopositive for vimentin, desmin, smooth muscle actin, synaptophysin, neuron-specific enolase, Bcl-2 and WT1 (nuclear); epithelial markers were negative. The definitive diagnosis of desmoplastic small round cell tumor was rendered with the demonstration of the characteristic EWS-WT1 gene fusion by fluorescence in situ hybridization. The current case emphasizes the utility of fluorescence in situ hybridization to demonstrate EWS-WT1 gene fusion in desmoplastic small round cell tumor with nonclassic morphologic and immunohistochemical features to avoid potential misdiagnosis.     

Ovarian Myxoma: Ultrastructural and Immunohistochemical Findings

The ultrastructural and immunohistochemical findings are reported in two ovarian myxomas, one of which was also associated with a sclerosing stromal tumor of the same ovary. Both neoplasms showed a myxoid, moderately cellular proliferation of spindle and stellate cells interspersed with areas of fibrosis and hemorrhage as well as delicate vascular spaces. Ultrastructurally, stellate neoplastic cells with irregular nuclei and occasional nucleoli were embedded in a mucinous and loose collagen matrix. Their cytoplasm showed abundant intracytoplasmic thin filaments that rarely condensed into poorly formed dense bodies. These thin filaments correlated with immunoreactivity for musclespecific actin and vimentin. The neoplastic cells showed no immunoreactivity with antibodies to desmin, S-100 protein, cytokeratin AE1 :AE3, factor Vlll-related protein, or placental alkaline phosphatase. These ultrastructural and immunohistochemical findings are consistent with myofibroblastic differentiation. These ancillary studies exclude important, clinically more aggressive differential considerations such as myxoid rhabdomyosarcoma, myxoid liposarcoma, myxoid neural tumors, mucinous adenocarcinoma showing pseudomyxomatous change, and myxoid-appearing endodermal sinus (yolk sac) tumor.