Intraparenchymal Epidermal Inclusion Cyst Within a Fibroadenoma in the Breast: A Case Report

Epidermal inclusion cysts are benign lesions that arises from the proliferation and entrapment of epidermal elements within the dermis, characterized by a lining of stratified squamous epithelium and an accumulation of keratin debris. While epidermal inclusion cysts are commonly located in areas such as the scalp and neck, their occurrence in the breast is rare. In some instances, the cyst can arise in atypical locations, including the nipple and parenchyma.This report presents a 40-year-old female patient who presented with a progressively enlarging lump in the right breast, initially diagnosed as a fibroadenoma through core needle biopsy 2 years after initial presentation. Imaging studies revealed a circumscribed mass, leading to surgical excision. Histopathological examination confirmed the presence of an intraparenchymal epidermal inclusion cyst within the fibroadenoma, a notable finding given its uncommon localization. This report emphasizes the necessity for thorough evaluation of breast masses and highlights the potential for epidermal inclusion cysts to occur in unusual presentations, contributing to the understanding of their pathogenesis and clinical implications in breast health.