[Granular cell tumor of the male breast. A case report].

Granular cell tumor of the male breast is an extremely rare neoplasm. The case of a 64-year-old man with a periareolar lump in the upper medial quadrant of his left breast of recent onset is reported. At clinical examination, it was a poorly circumscribed, irregular, hard, mobile 1 cm mass. No axillary lymph nodes were palpable. The patient was submitted to ultrasound scan which showed a 1 cm periareolar solid hypoechoic lesion with an acoustic shadowing and subsequently to fine needle biopsy that revealed the presence of also atypical ductal hyperplasia. For this reason he was submitted to excision biopsy. The definitive histology was of granular cell tumor. The immunohistochemical investigations showed an intense positiveness for S-100 protein; the staining with PAS showed a diffuse positiveness. At 18 months after treatment the patient had no recurrence of disease. Granular cell tumor of the male breast is a neoplasm whose differential diagnosis with carcinoma is often possible only with definitive histology. For this reason, also in front of a mammary lump strongly suspicious for carcinoma, it's always necessary to think it can be this neoplasm and therefore to wait for the necessary histopathologic confirmation.