A 6-year-old girl presents with a left breast mass. Her mother first noticed it a day before and is very concerned because both the child's maternal grandmother and maternal aunt have had breast cancer. It is firm, smoothly circumscribed, and slightly eccentric under the left areola. The right breast is unremarkable. You suggest

Breast cancer is vanishingly rare in children with on 60 cases reported in the English literature even in patients with the BRCA mutations. Therefore, needle biopsy and mammogram are unlikely to be helpful. The most likely tumor in this case is a benign fibroadenoma. Removal of breast masses in prepubescent girls carries a strong possibility of damage to the involved breast bud with subsequent hypoplasia of the adult breast. In this case, it would be better to defer excision until after puberty unless the mass continues to enlarge or becomes symptomatic.