Solid apocrine carcinoma of the skin: report of a rare adnexal neoplasm mimicking lobular breast carcinoma.

The so called 'sweat gland carcinoma' is a rare skin malignancy. The differentiation between apocrine and eccrine neoplasms remains difficult. Skin tumors of the axilla are often suspected to be metastasis of other neoplasms in particular breast cancer. A 71-year-old man presented with a morphea-like plaque of the right axilla which in punch biopsy was first suspected as metastasis of primary lobular breast carcinoma. After further clinical and laboratory work up including immunohistochemistry the original diagnosis of a breast cancer had to be changed to solid apocrine carcinoma of the skin. Wide excision with en-bloc axillary lymph node dissection was performed. Final tumor stage was pT2 N0 M0 (V0 L0). No adjuvant treatment was necessary, and there is no evidence of disease after 3 years. Solid apocrine carcinoma of the skin is a rare variant with apocrine differentiation. A survey of the stereotypical presentation of this lesion and a comparison with lobular breast carcinoma and other types of apocrine carcinoma of the skin is given.