A Case of Digital Intraosseous Epidermoid Inclusion Cyst of the Distal Phalanx

Intraosseous epidermoid inclusion cyst is a very rare cystic lesion of the bone, that has been reported primarily in middle-aged men. A congenital etiology has been proposed, although post-traumatic or iatrogenic events remain the most prevalent hypotheses. A 61-year-old woman visited Soonchunhyang University Gumi Hospital complaining of painful swelling of her right middle finger. Radiologic findings of the lesion showed a well-defined, lytic, expansile lesion originating at the tip of the distal phalanx. Preoperative imaging suggested benign cartilage tumors such as enchondroma or acute osteomyelitis. Intralesional curettage, culture, and biopsy were performed. Histopathological analysis demonstrated stratified squamous epithelium with keratinized cellular debris, consistent with a diagnosis of digital intraosseous epidermoid inclusion cyst. We present a case of an epidermoid inclusion cyst originating at the tip of the distal phalanx of the right middle finger.