Malignant adnexal cutaneous tumor of the scalp: a case report of difficult differential diagnosis between metastatic breast cancer and primary sweat gland tumor

The authors describe the case of a 71-year-old female patient who initially went to the dermatologist to assess a scalp skin tumor. This lesion was submitted to an incisional biopsy, performed by dermatologist herself, and the result of the anatomopathological examination and immunohistochemical study showed a preliminary diagnosis of metastasis of breast carcinoma. The patient had no history of breast cancer and, in view of this result, she was referred to consult with the mastologist, who carried out an investigation of breast nodules in search of the possible primary focus of the carcinoma, through imaging exams, biopsies and mammotomy, without finding any possible primary focus on the breasts. Finally, the lesion on the scalp was removed in its entirety by the plastic surgeon and a new exam of pathological anatomy and an immunohistochemical study confirmed the diagnosis of metastasis of breast carcinoma. In view of these results, the authors discuss the difficulty in diagnosing differentiation from primary or metastatic neoplasm of the scalp, with the resources currently available, until the conclusion that it was a primary carcinoma of the sweat gland.