Fibroadenoma in Axillary Supernumerary Breast in a 17-Year-Old Girl: Case Report

In this report, we describe a rare case of fibroadenoma in an accessory breast in a young woman. There are a fewer than 40 reports in the world about this subject, of which differential diagnoses include: cancer in axillary supernumerary breast, hidradenitis, axillary lymphadenomegaly, lipomas, anexial cutaneous neoplasia, cysts, and phylloides tumor. The combination of clinical examination, ultrasound, and cytology leads to adequate treatment, especially surgical. The diagnosis could be confused because of findings from cytology. In this case, because of the clinical and sonographic findings and multiple differential diagnosis, only the histopathological study was used to confirm the diagnosis. Despite its high sensitivity, cytology has low specificity and could create false positive results. However, atypical lesions can be seen in fibroadenomas, especially in younger patients, pregnant patients, and in patients who use hormonal contraception. Although there are a few reports, our case report is similar to current medical registers and, after surgical treatment, our patient had an excellent prognosis.