Primary cutaneous apocrine carcinoma: A challenging case report.

Introduction: Primary cutaneous apocrine carcinomas of the axilla represents an extremely rare entity, with <200 cases reported in the literature. It can be challenging, even almost impossible, to distinguish histologically from metastases of breast origin. We herein present the first case of an axillary cutaneous apocrine adenocarcinoma followed and treated in our institute.

Case Presentation: A 58-year-old man with a history of myopathy, presented for a right axillary swelling. Physical examination revealed the presence of a 10 cm right axillary mass, no palpable adenopathy, and bilateral gynecomastia. A biopsy of the mass was performed, showing a pattern consistent with a secondary localization of mammary neoplasia. Breast and distant radiological examinations were negative. The tumor markers' levels were not raised. Therefore, the patient underwent surgery with a large excision, a right axillary lymph node dissection, covered with a pedicled pectoralis major flap. Histological and immunohistochemical examinations showed a high expression of CK7 with a negative expression of TTF1, RH, PSA, and CK20. The diagnosis of an apocrine adenocarcinoma from cutaneous origin was confirmed.

Clinical Discussion: Primary cutaneous apocrine carcinomas are a group of uncommon malignant adnexal tumors, whose diagnosis is almost impossible to confirm preoperatively. Wide, local excision with clear margins, with or without lymph node dissection is the standard treatment.

Conclusion: This case illustrates the importance of clinico-pathological correlation of skin cancers, especially apocrine ones. Clinical particularity and careful histological analysis are used to guide the diagnostic approach.