Granular cell tumor in the breast mimicking breast carcinoma

Granular cell tumor is also known as a granular cell myoblastoma, Abrikossoff's tumor, granular cell nerve sheath tumor or granular cell scwhannoma. It is a rare soft-tissue mass that can develop in any soft tissue. Most commonly it appears in the tongue (40%), the oral cavity or in the subcutaneous tissue. In rare occasions it is reported as a breast mass, mimicking a carcinoma. Not only clinically, but also on mammography, ultrasonography and macroscopically. Diagnosis can only be made on histology, emphasizing once again the importance of a thorough pre-operative multi-disciplinary assessment. We describe a case in which a woman presents herself with a palpable nodule in the breast in which clinical investigation, mammography and especially sonography indicated the presence of a malignancy. Only after we conducted a core biopsy for pre-operative histological investigation, we could make the diagnosis of a granular cell tumor, preventing an unnecessary mastectomy. The patient refused however local excision and was followed up with mammography and sonography.