Cutaneous leiomyosarcoma originating in a symplastic pilar leiomyoma: a rare occurrence and potential diagnostic pitfall

A case of cutaneous leiomyosarcoma originating in a symplastic pilar leiomyoma is described. The patient was a 60‐year‐old man who presented with a painless nodule on his chest. Thorough clinical examination did not reveal any evidence of tumor elsewhere. A punch biopsy was performed which showed a benign spindle cell neoplasm with focal cellular pleomorphism that had smooth muscle differentiation and was clearly originating from the arrector pili muscle, consistent with a cutaneous symplastic pilar leiomyoma. Immunohistochemical studies were performed and the tumor cells were strongly positive for smooth muscle actin (SMA) and desmin. Given the clinical information of a mass on the chest, clinical evaluation was recommended and a re‐excision was performed. Histologically, the re‐excision showed two distinct populations of cells. The upper portion of the tumor mirrored the initial biopsy; however, the base of the tumor showed hypercellular areas composed of spindle cells with marked pleomorphism and increased number of mitoses. The diagnosis of a cutaneous leiomyosarcoma originating in a symplastic pilar leiomyoma was given. This is the first report of this association of such occurrence reported in the literature. Fons ME, Bachhuber T, Plaza JA. Cutaneous leiomyosarcoma originating in a symplastic pilar leiomyoma: a rare occurrence and potential diagnostic pitfall.     

Atypical pilar leiomyoma: cutaneous counterpart of uterine symplastic leiomyoma?

Four cases of cutaneous leiomyoma with cytologic atypia are reported. All four cases were adult men ranging in age from 33 to 92 years of age. Clinical diagnoses were diverse and included epidermal inclusion cyst, scar, nevus, dermatofibroma, squamous cell carcinoma, and basal cell carcinoma. Histological examination of all four lesions revealed a relatively circumscribed, mild to focally moderately cellular, dermal proliferation of large, irregularly shaped spindle cells in a fascicular arrangement. Some cells contained large irregular nuclei and abundant cytoplasm; others were multinucleate. Moderate to focal marked pleomorphism and rare mitotic figures were present, raising the possibility of leiomyosarcoma; however, the sparse mitotic activity and low cellularity did not warrant this diagnosis. This study suggests that cutaneous leiomyomas may exhibit bizarre or "symplastic" patterns analogous to their uterine counterparts.     

Association of multiple familial cutaneous leiomyoma with a uterine symplastic leiomyoma

We describe a patient who has familial cutaneous leiomyoma in association with a symplastic uterine leiomyoma. This association has not been described previously.     

Atypical pilar leiomyomatosis: an unusual presentation of multiple atypical cutaneous leiomyomas

Cutaneous leiomyomas are relatively common benign smooth muscle tumors that may arise as solitary or multiple lesions. Rare forms with cytologic atypia, and features similar to symplastic leiomyomas of the uterus, have been described. We report a case of multiple cutaneous atypical leiomyomas occurring in a 43‐year‐old man with long history of lesions of the right lower leg and a family history of leiomyomatosis. Twenty of the lesions were excised due to pain and were examined histopathologically. All the lesions exhibited features described in atypical leiomyomas of the skin including increased cellularity, nuclear atypia and pleomorphism, and low mitotic activity. The biologic potential of cutaneous atypical leiomyomas is uncertain. Only a few case reports exist in the literature with the majority occurring as solitary lesions. Most of the reported atypical leiomyomas have behaved in a benign fashion. However, a rare account of transformation to leiomyosarcoma emphasizes the need for long‐term follow up of these patients. Herein, we describe a case of multiple atypical cutaneous leiomyomas arising in the setting of familial leiomyomatosis.     

Symplastic glomus tumor – a rare but distinct benign histological variant with analogy to other 'ancient' benign skin neoplasms

A 78-year-old woman presented with a nail deformity of the index finger of the left hand associated with paroxysmal pain upon cold exposure. Histologically, a well-circumscribed tumor of 3 mm diameter was found in the dermis. The neoplastic cells in some areas were of pronouncedly variable size and cytomorphology, mostly epithelioid in shape, with eosinophilic cytoplasm and indistinctly defined cell borders. Pronounced nuclear pleomorphism and atypia were striking features, but no mitotic figures were noted. Multinuclear cells were present as were numerous small-to-medium vessels throughout the tumor. The tumor stroma showed myxoid areas.
Immunohistochemistry showed cytoplasmic and membranous expression of smooth muscle actin and vimentin. The histological features and immunoprofile were consistent with the diagnosis of symplastic glomus tumor, a rare histological variant, which has been defined as a glomus tumor exhibiting marked nuclear atypia, in the absence of any other criteria for malignancy. The biological behavior of the tumor is benign. It is essential to differentiate this entity from malignant glomus tumor, which has metastatic potential. Even prominent cellular atypia and nuclear pleomorphism in a glomus tumor as in our case is not a marker of malignancy in the absence of additional criteria.     

Symplastic hemangioma: report of two cases

Symplastic hemangioma is characterized by degenerative atypia of vascular smooth muscle and interstitial cells within a pre-existing vascular lesion with minimal endothelial cell atypia. We describe an additional two cases of this distinctive but poorly recognized entity. On histology, both lesions revealed a cirsoid aneurysm-type appearance with thick-walled and variably dilated blood vessels. The vascular endothelial cells showed mild nuclear hyperchromasia with no multilayering or mitoses. The atypical cells, either located within the vascular smooth muscle wall or within the interstitium, were spindle or epithelioid with varying degrees of hyperchromasia, nuclear enlargement, pleomorphism, and multinucleation. Perivascular hemorrhage, vascular thrombosis, and focal papillary endothelial hyperplasia were uniformly present. The variably fibrous to edematous stroma showed hemosiderin deposits and a mononuclear inflammatory infiltrate. Clusters of adipocytes were present within the superficial dermis. Rare atypical mitoses and occasional bizarre lipoblast-like stromal cells were identified in one tumor. Immunohistochemistry showed focal smooth muscle actin positivity in the pleomorphic cells of the vascular walls. CD68 and CD34 stained occasional stromal cells in the interstitial location. Both the cases showed no recurrence. The bizarre cytologic changes are interpreted as degenerative in nature and probably akin to that observed in ancient schwannoma and uterine symplastic leiomyoma.     

Symplastic trichodiscoma: a spindle-cell predominant variant of trichodiscoma with pseudosarcomatous/ancient features

Trichodiscomas are hamartomatous lesions of the follicular unit and of its surrounding stroma composed of epithelial and mesenchymal tissue elements. The dominating tissue element in trichodiscoma is the central fibrous stroma, encircled by prominent clusters of sebaceous lobules that resemble mitts. Rare variants of trichodiscomas with CD34-positive spindle cell-pedominant stroma have been described. We report a case of spindle cell-predominant trichodiscoma with prominent pseudosarcomatous/ancient features consisting in numerous large atypical spindle cells with frequent multinucleation, with no mitotic activity. The cytological changes were similar to those described in ancient schwannoma and symplastic hemangioma. We propose to call this lesion symplastic trichodiscoma. Only 1 previous case of fibrofolliculoma with pseudosarcomatous/ancient changes has already been reported. Although such lesions can appear worrisome at first glance, their benign evolution, the absence of mitosis, and the phenotypic studies excluding malignant differential diagnoses like atypical fibroxanthoma are reassuring. The precise pathogenesis of the symplastic features in schwannoma as in trichodiscoma/fibrofolliculoma is not known yet.     

A unique biphasic variant of cutaneous fibrous histiocytoma with a storiform pattern and intralesional pigmented melanocytes: "storiform melano-fibrous histiocytoma"

Dermatofibromas (cutaneous fibrous histiocytomas) are common cutaneous neoplasms of mesenchymal origin. They are often associated with epidermal hyperplasia and increased basal layer pigmentation. There have been reports of a spectrum of melanocytic lesions associated with dermatofibromas ranging from junctional nevi to malignant melanomas, some of which may be coincidentally associated. We report a case of a long-standing storiform fibrohistiocytic lesion devoid of cytological atypia, lacking extension into subcutaneous fat, not demonstrating the t(17;22) DFSP translocation yet showing diffuse and strong CD34 immunoreactivity and containing pigmented spindle shaped melanocytic cells admixed with the fibrohistiocytic component. This case raises a nosological debate given the histological, immunophenotypic and cytogenetic findings.     

Malignant cutaneous glomus tumor presenting as a rapidly growing leg mass in a pregnant woman

A 21-year-old pregnant woman presented with a rapidly growing >2 cm nodule on her right leg, involving dermis and subcutaneous tissue. Histologically, the tumor was composed of sheets and nests of neoplastic cells with variable cytomorphology, including typical round to ovoid glomus cells with clear cytoplasm and well-defined cell borders, small cells and spindle cells. Numerous medium to large vessels were present throughout the tumor. Moderate- to high cellularity, nuclear atypia and frequent mitotic figures (42 MF/50 High power field (HPF)) were noted. Immunohistochemistry showed cytoplasmic and membranous expression of actin (HHF-35) and membranous expression of type IV collagen. The histologic features and immunoprofile were consistent with the diagnosis of malignant glomus tumor, a rare soft tissue neoplasm that typically arises on the extremities. Histologic features that infer malignancy in glomus tumors include the combination of large size (>2 cm) and deep location, or atypical mitotic figures, or moderate to severe cytologic atypia with high mitotic activity (>5 mitoses /50 HPF). Although our case was superficially located, the nuclear atypia and mitotic rate, as well as the large size, fulfilled the criteria for a malignant glomus tumor.     

Granular cell atypical fibroxanthoma: report of two cases

Two cases of an uncommon histopathological variant of atypical fibroxanthoma (AFX) are described. Even though both lesions presented as clinically conventional atypical fibroxanthoma, histopathology disclosed a neoplasm composed of cells with granular change that was negative for S100 staining, and showed prominent pleomorphism, severe nuclear atypia, and a high mitotic index. Degenerative change may explain the granular phenotype in these two cases of AFX. The differential diagnosis with primitive nonneural granular cell tumor is discussed.     

The value of immunohistochemistry in atypical cutaneous fibrous histiocytoma

Atypical cutaneous fibrous histiocytoma is a rare variant of dermatofibroma/fibrous histiocytoma characterized by striking atypia, thus resembling atypical fibroxanthoma. We studied 9 examples of ACFH histopathologically and immunohistochemically to investigate the nature of these atypical cells. Histology revealed ill-defined skin nodules, which were polypoid in 6 cases. A minority of mononuclear and giant cells (< 5%) revealed striking pleomorphism and showed large nuclei with prominent nucleoli. Immunohistologically, the atypical cells expressed vimentin, but were negative for S-100 protein, the keratin marker MNF116, alpha smooth muscle actin, CD34, factor XIIIa, and monocyte/macrophage markers Ki-M1p, KP1 (CD68), and MAC387. Positivity for MiB1 was very modest (< 1%) and limited to small- and medium-sized, inconspicuous cells. Multinucleate giant cells proved to be heterogenous, on one hand cells with differentiation toward macrophages with positivity for Ki-M1p and KP1, on the other toward fibroblasts positive for vimentin only. These immuno-histochemical results for differentiation markers in atypical cutaneous fibrous histiocytoma are similar to our previous findings and data in atypical fibroxanthoma; MiB1 helps to separate these entities from each other as the latter shows a very high proportion of proliferative atypical cells corresponding to the numerous mitoses seen in routine sections.     

Hyperkeratotic lesion of the nipple revealing cutaneous leiomyoma

BACKGROUND: Leiomyoma of the nipple and areola is a rare benign neoplasm. We report the case of a patient with leiomyoma of the nipple presenting as a hyperkeratotic plaque. OBSERVATION: A 23-year-old patient presented with a five year history of a papillomatous, hyperkeratotic, painful plaque originating in her right nipple. Histological examination of a punch biopsy showed hyperkeratosis of the epidermis with dilatation of the lymphatic vessels within the dermis. Surgical excision revealed a proliferation of smooth muscle fibres, leading to diagnosis of leiomyoma. DISCUSSION: The clinical and histological features were initially consistent with idiopathic naevoid hyperkeratosis of areola. However, associated pain is uncommon in idiopathic lesions. This unusual feature led us to surgical excision enabling the diagnosis of leiomyoma. A hyperkeratotic lesion of the nipple may be associated with benign or malignant neoplasms, hamartoma or chronic dermatoses, or it may be idiopathic. In the present case, the hyperkeratotic lesion revealed subareolar leiomyoma. This is an uncommon clinical presentation not previously seen in medical observations, since leiomyoma usually presents as a firm, painful lump in the subareolar region.     

Primary cutaneous epithelioid rhabdomyosarcoma: a rare,recently described entity with review of the literature

We report a case of a primary cutaneous epithelioid rhabdomyosarcoma that presented as a single raised pink‐purple lesion (3.3 × 2.2 cm) on the left base of neck in a 75‐year‐old man. Histopathologic examination revealed an exophytic, nodular tumor within the dermis and superficial subcutis with overlying ulceration. The tumor exhibited sheet‐like growth, infiltration of adjacent structures, and was composed of uniform epithelioid cells with abundant eosinophilic cytoplasm and eccentrically placed vesicular nuclei with irregular nuclear contours and prominent central nucleoli. Numerous mitotic figures were present [28/10 high power fields (HPF)] but only mild cytologic pleomorphism was identified. By immunohistochemistry, tumor cells were diffusely and strongly positive for desmin and MYOD1. Focal positive staining for myogenin and cytokeratin CK903 was identified. Stains for Melan‐A, S‐100, SOX10, p63 and CK5/6 were negative. These histopathologic and immunophenotypic features support a diagnosis of epithelioid rhabdomyosarcoma. No evidence of a deep soft tissue primary lesion was identified. In summary, epithelioid rhabdomyosarcoma can present as a primary cutaneous lesion and dermatopathologists should be aware of this entity.     

Diffuse cutaneous mastocytosis with multiple cutaneous mastocytomas

A patient with diffuse cutaneous mastocytosis, present since birth, developed several cutaneous mastocytomas without any symptoms after puberty. Although the histological picture of the tumours, showing nuclear atypia, mitotic figures and varying metachromasia of the granules, raises suspicion of systemic involvement, this has not appeared so far. The absence of symptoms could be due to the synthesis of an abnormal secretory product by the mast cells, which is supported by the absence of oedema and dilated blood vessels in the presence of extensive degranulation and by the unusual ultrastructural picture of the mast cell granules, i. e. little electron density with the almost complete absence of lamellar and crystalline structures.     

Amelanotic Spitzoid Melanoma in the Burn Scar of a Child

Abstract: We report a 3-year-old girl with a rapidly growing, amelanotic, nodular melanoma developing within a burn scar over the dorsal aspect of the left foot. Histologically, the lesion was spindle cell and exhibited lack of maturation, cellular atypia, and scattered mitotic figures. Twenty five percent of the tumor cells were positive for proliferating cell nuclear antigen by immunohistochemical stain. A left inguinal lymph node was also positive for regional metastasis. The child died with disseminated metastases 13 months after the lesion was removed.     

平滑肌肉瘤

报告1例平滑肌肉瘤.患者男,65岁.因左胫前暗褐色肿块1年伴疼痛1个月就诊.左胫前肿块由数枚黄豆至蚕豆大暗褐色结节融合,高出皮面,部分结节表面破溃,可见新鲜的肉芽组织,肿块质地较硬,活动度小,压痛明显.皮损组织病理学检查示真皮内境界清楚的梭形细胞增生,梭形细胞纵横交错排列成柬状.梭形细胞胞质呈嗜酸性.杆状核两端钝圆,部分核周见空泡,可见明显的核分裂象;免疫组化染色检查:波形蛋白(+)、肌动蛋白(+)、平滑肌肌动蛋白(+)、S-100蛋白(-).诊断:平滑肌肉瘤.     

Subungual leiomyoma in the left thumb of a 16‐year‐old female

Cutaneous leiomyomata, which are benign smooth muscle neoplasms, commonly present as dermal‐based nodules or papules with smooth borders and firm consistency. Digital, particularly subungual leiomyomata are quite rare. A 16‐year‐old female presented to nail clinic complaining of discoloration of the lunula of the left thumbnail for 2.5 months. On initial examination, a pink longitudinal band was present in the center of the nail plate, with yellow discoloration and distal onycholysis. The patient had only mild tenderness with firm palpation, and did not recall trauma of the area. A nail matrix biopsy was performed to determine the etiology of the lesion. Microscopic examination demonstrated a well‐demarcated dermal‐based spindle‐cell fascicular proliferation. Bland cells exhibited eosinophilic cytoplasm and elongate nuclei with blunt ends and minimal cytologic atypia. Prominent nucleoli, mitoses or necrosis were not appreciated. Immunohistochemical stains for smooth muscle actin and caldesmon highlighted the cells. Contrarily, S‐100, epithelial membrane antigen, p63, factor XIIIa, CD34, CD68 and p75 were all negative. Ki‐67 showed a low proliferative index. The immunoprofile combined with the morphologic features were interpreted as subungual leiomyoma. Subungual leiomyoma is a very rare diagnosis. We seek to bring awareness and expedite the diagnosis in patients with this lesion.     

Primary cutaneous biphasic sarcomatoid basal cell carcinoma with myoepithelial carcinoma differentiation: A new variant

Isolated cases of basal cell carcinoma (BCC) with partial myoepithelial component have been described. However, myoepithelial differentiation has not been described in sarcomatoid basal cell carcinomas, which usually show features resembling osteosarcoma, chondrosarcoma, or leiomyosarcoma. We report a case of an 87‐year‐old man with a forehead lesion that histologically showed a minor component of conventional nodular BCC in transition with a major biphasic sarcomatoid growth composed of invasive spindle‐cell and epithelial‐like components, the latter with a reticular pattern and scattered ductal structures. Both components showed cytological atypia and high mitotic rate (26/10HPF), with atypical mitotic figures. BER‐EP4 immunostaining was exclusively found in the nodular BCC component whereas the sarcomatoid component revealed immunostaining for α‐smooth muscle actin (SMA), muscle‐specific actin (MSA), calponin, and p63 in both epithelial‐like and spindle‐cell populations. Focal immunoreactivity was observed in the epithelial component for S100 and glial fibrillary acidic protein (GFAP). Furthermore, EWSR1‐PBX1 gene fusion was also detected. This is to our knowledge, the first fully documented case of biphasic sarcomatoid BCC with myoepithelial carcinoma differentiation.     

Two cases of male nipple leiomyoma: idiopathic leiomyoma and gynecomastia-associated leiomyoma

We describe 2 cases of male nipple leiomyoma. A 70-year-old man had a painful subcutaneous tumor on his left nipple of 6 months duration. Histopathology disclosed dermal spindle cells with oval-shaped nuclei forming interlacing bundles with irregular pattern. Glandular elements were absent. The spindle cells were positive to α-smooth muscle actin, desmin, and vimentin. Estrogen receptor (ER) and progesterone receptor (PrR) were negative. We diagnosed this case as male leiomyoma of the nipple. Another patient was a 61-year-old man with gynecomastia induced by spironolactone of 6 months duration. He also had a painful nodule on his left nipple and histopathology disclosed spindle-shaped tumor cells as in the previous patient. The tumor was accompanied by glandular elements in the deep dermis and subcutaneous tissue, which showed apocrine secretion and were positive for α-smooth muscle actin, ER, and PrR. These glandular elements were interpreted as mammary gland. But ER and PrR stain did not show positive results for leiomyoma in the upper dermis. To the best of our knowledge, this is the first report of male idiopathic and gynecomastia-induced leiomyoma with ER and PrR staining.     

Benign cutaneous pseudoglandular schwannoma: a case report

Schwannoma is a common peripheral neural neoplasm that could present as a primary skin lesion. In addition to typical schwannoma with classic Antoni A and Antoni B areas, many variant types have been described, such as plexiform, cellular, epithelioid, and ancient schwannomas. Glandular schwannoma is a rare variant characterized by the presence of glands in an otherwise typical schwannoma. There are also a few reported cases in the literature of pseudoglandular schwannoma from central nervous system, eye, submandible, and shoulder, in which the gland-like structures were lined by Schwann cells. We report here a patient with a benign cutaneous schwannoma composed of predominantly gland-like spaces that contained mucinous material and were lined by Schwann cells confirmed by immunohistochemistry and ultrastructural studies. The tumor was well circumscribed and showed minimal cytologic atypia, indicating benignity. We report this unusual case of benign cutaneous pseudoglandular schwannoma to further awareness of the morphologic diversity of schwannoma.