Incidental finding of delayed transformation of fibroadenoma to phyllodes tumor in young female: A Case Report

Abstract

Phyllodes tumors arising from fibroadenomas are rare occurrences, particularly in young females. We present a case of a 27-year-old woman with a history of benign left breast fibroadenoma, who presented with right flank pain. Initial investigations revealed a significant enlargement of a previously identified benign left breast fibroadenoma. Imaging studies demonstrated a macrolobulated solid non-calcific lesion, notably larger than before, prompting referral to a breast clinic. Subsequent diagnostic ultrasound and contrast-enhanced MRI revealed a lesion displaying features concerning for phyllodes tumor. Biopsies performed in 2021 and at presentation (2022) indicated a transition from solitary benign fibroepithelial lesion (fibroadenoma) to borderline phyllodes tumor. Surgical excision lumpectomy was undertaken, with histological examination confirming borderline phyllodes tumor, stromal hyperplasia with mild cytologic atypia, and a notable mitotic rate of 9 per 10 high-power fields. This case underscores the importance of vigilance in monitoring fibroadenomas, as they may undergo transformation into phyllodes tumors.