Squamous Cell Carcinoma Arising from Epidermal Inclusion Cyst of Breast: Imaging Findings and Literature Review.

Commonly, epidermal inclusion cysts (EICs) are benign cutaneous lesions that are lined with stratified squamous epithelium and may occur in all body parts, including the breasts. EICs in the breast (EICB) are commonly encountered clinically; it may be under-reported because of their mild and non-specific clinical presentation. Malignant transformation of EICs is extremely rare, occurring 0.011%-0.045%. Presently, we report a rare case of squamous cell carcinoma arising from an EICB of a woman with invasive ductal carcinoma.