Sarcomatoid melanoma is a rare type of melanoma lacking typical histologic features of melanoma and often lacks expression of S100 protein and melanocyte-specific markers. Given the rarity of this entity, its clinicopathologic findings are not well defined. We report 2 cases of sarcomatoid melanoma received in consultation: a 65-year-old woman with a right breast mass and a 62-year-old man with a left plantar heel mass. Both lesions were ulcerated, pedunculated, highly cellular proliferations of atypical spindle cells arranged as fascicles and/or sheets. The tumor cells of the breast mass expressed CD10 and vimentin diffusely but S100 protein only focally. The tumor cells of the heel mass lacked expression of melanocytic markers altogether, except for weak, very focal S100 protein expression. At the junctional edge of the breast mass and in the ulcer base of the heel mass, focal precursor melanoma was present and exhibited melanocytic differentiation. We report these cases to emphasize the importance of meticulous histologic inspection at the lesion's edge and/or ulcer base to correctly identify the conventional precursor melanoma in these rare lesions to ensure appropriate diagnosis and subsequent clinical management as treatment options may be significantly different from those offered for sarcomas.
Desmoplastic melanoma is an uncommon form of melanoma characterized by atypical spindled melanocytes and abundant collagen deposition. It typically presents in sun-damaged skin of the elderly as an amelanotic, indurated lesion. It has a higher tendency for local recurrence but lower risk of lymph node metastasis vs. conventional malignant melanoma. We report two cases in women aged 59 and 66 who presented with small scalp lesions clinically suggestive of alopecia. The differential diagnosis included alopecia areata, lupus erythematosus and lichen planopilaris. Biopsies performed according to alopecia protocol were reviewed at our institutions. Biopsies revealed atypical spindled and nested epithelioid melanocytes set in a sclerotic dermis with scattered lymphoid aggregates and immunohistochemical expression of S100 protein, features diagnostic of combined desmoplastic melanoma. Wide local excision with skin graft was performed on the older patient. Excision showed combined desmoplastic melanoma with a Breslow thickness of 8.5 mm with melanoma in situ identified in the adjacent epidermis. The other patient sought treatment elsewhere and was lost to follow up. These cases illustrate desmoplastic melanoma as an unusual etiology and dangerous clinical pitfall in patients with scar-like alopecia. To the authors' knowledge, these represent the second and third reported cases of desmoplastic melanoma presenting as primary alopecia neoplastica.
Cylindromas are benign epithelial neoplasms derived from cutaneous eccrine adnexal structures. These tumors are most commonly encountered on the head, neck, and scalp of older women. In rare instances, solitary cylindromas may arise at other body sites. In the current case, a cylindroma of the skin of the breast was diagnosed by complete excision. Immunohistochemical studies confirmed the tumor cells to be immunoreactive with cytokeratin AE1/3, cytokeratin 5/6, cytokeratin 7, p63, and SOX10. The neoplastic cells were also noted to be immunoreactive with markers typically expected to be positive in ductal epithelium of the breast including GATA3, mammaglobin, and E-cadherin. The case emphasizes the importance of correlating clinical setting, imaging studies, patient history, and careful microscopic evaluation in arriving at an accurate diagnosis. This case also illustrates the point that not all “breast” tumors that are confirmed to be positive for GATA3, mammaglobin, and E-cadherin are derived from mammary ducts.
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