Recurrent bilateral giant breast fibroadenomas with a somatic PIK3CA p.G106V mutation: case report and review of current evidence.

[BACKGROUND] Fibroadenomas are common benign breast tumors, but recurrent bilateral giant fibroadenomas are rare. Recent studies suggest genetic factors, such as mutations, may influence tumor behavior.

[CASE PRESENTATION] A 23-year-old woman with prior multiple fibroadenoma excisions presented with progressively enlarging bilateral breast masses and marked deformity. Imaging revealed multiple well-circumscribed lesions, the largest measuring 7.5 cm. Serum prolactin was elevated; estradiol and progesterone were normal. She underwent bilateral excision with reduction mammoplasty and nipple–areolar reconstruction. Histology confirmed fibroadenomas with epithelial hyperplasia; immunohistochemistry showed diffuse estrogen receptor positivity (>90% of cells) and a Ki-67 index of 5–10%. Next-generation sequencing detected a somatic c.317G>T (p.G106V) mutation.

[CONCLUSION] Integration of histological, hormonal, and molecular findings can guide individualized management of recurrent fibroadenomas. Large-scale studies are required to assess the prognostic significance of mutations in benign breast tumors.

[SUPPLEMENTARY INFORMATION] The online version contains supplementary material available at 10.1186/s12905-025-04032-3.