Epidermal inclusion cysts are formed by inclusion of keratinizing squamous epithelium within the dermis, resulting in a cyst filled with lamellated keratin. These benign cysts are usually very small and intradermal subcutaneous lesions. They can occur anywhere in the body although they are more common on the face, trunk, neck, extremities and scalp. Only a few cases of epidermal cysts of the breast have been reported in the literature. An epidermal inclusion cyst of the breast can result in several problems, even if the size is unusual. We encountered a case of a giant sized epidermal inclusion cyst of the breast initially mimicking a large fibroadenoma or phyllodes tumor.