Primary aneurysmal cyst: bone type in the breast.

A 60-year-old women presented with one month's history of a large breast lump. On examination she had irregular hard mass occupying the central and outer quadrants of the right breast with no palpable lymph nodes. Fine needle aspiration cytology (FNAC) diagnosis was a benign stromal lesion. In view of the large size, a simple mastectomy was performed. We are reporting this case of primary extrasseous aneurysmal cyst of the bone in the breast as the first case described in the literature.