腋窩副乳発生と考えられる若年性線維腺腫の１例

A case is２０years old woman. She had previously noticed a mass in the left axilla. The mass grew, so she went to the hospital. Ultrasonography revealed a ７１ × ５１ mm well-defined tumor in the left axilla. We suspected a benign tumor but could not rule out axillary lymph node metastasis or accessory breast cancer. The findings of fine needle aspiration cytology suggested fibroadenoma or phyllodes tumor. Although we diagnosed fibroadenoma by needle biopsy, a definitive diagnosis was made by tumor resection because it is located in the axilla and large in size, and other diseases such as phyllodes tumors can be distinguished. The histopathological diagnosis of the excised specimen was juvenile fibroadenoma. We report a case of juvenile fibroadenoma arising from the axillary accessory mammary gland.