Case report: A rare case of eccrine carcinoma

Solitary Vulvar Syringoma With Deep Extension; Potential for Misdiagnosis as the Microcystic Adnexal Carcinoma (MAC)

ABSTRACT

A 43-year-old woman presented with a palpable, pruritic, minimally painful right vulvar lesion. Physical examination revealed approximately 2.0-cm tender nodule at 70' clock in the right labia majora. Histological sections of the excision specimen showed an unremarkable epidermis with large, well-circumscribed dermal proliferation with extension to the reticular dermis. Within this proliferation are small solid and ductal structures relatively evenly distributed in the sclerotic stroma. The epithelial elements consisted of monomorphous cuboidal cells and assumed round, oval, curvilinear, or have other peculiar geometric shapes, including "comma-like" or "tadpole"-like configurations. The tumor cells were positive for CEA, EMA, and estrogen receptor and negative for progesterone receptor. The clinical presentation and the deep extension of the tumor were similar to the microcystic adnexal carcinoma. Although a syringoma generally presents with multiple lesions and usually involves the superficial dermis, a syringoma with deep extension was favored based on the lack of follicular differentiation, atypia, mitoses, and perineural invasion. Microcystic adnexal carcinoma and syringoma have a morphologic overlap and are misdiagnosed in 30% of the cases. Thus, it is exceptionally important for pathologists to be aware of and be able to distinguish these entities. To the best of our knowledge, this is the first case of a solitary, painful vulvar syringoma with deep extension.

Poorly Differentiated Metastatic Carcinoma of Possible Eccrine Sweat Gland Origin

Sweat gland carcinomas are a rare group of cancer, representing less than .01% of all diagnosed skin malignancies. We report the case of a 32-year-old male who presented with a fungating lesion on the posterolateral side of his left knee. Immunohistochemical results were positive for cytokeratin 5/6 and cytokeratin 7, consistent with possible eccrine gland origin. Our patient underwent wide local excision of the mass with lymph node dissection. Pathology confirmed the diagnosis of poorly differentiated carcinoma of possible adnexal, eccrine gland origin. He completed taxol/cisplatin-based chemotherapy and radiation. Surveillance imaging showed bilateral lung nodules, a right pleural effusion, and peritoneal carcinomatosis, which were diagnostic of metastatic carcinoma. He started carboplatin and epirubicin chemotherapy and has been doing well. Because standard of care treatment options for metastatic eccrine carcinoma have not been developed, it is imperative to report these cases to better understand these complex tumors and their treatment.