Epidermoid Cyst after Groin Flap Mimicking Malignancy

ABSTRACT

Epidermoid cyst is a benign tumor containing a layer composed by stratified squamous epithelium and filled with keratin. The epidermoid cyst after soft tissue damage such as bite, laceration could be caused by implantation of epidermal cells. There are reports of epidermoid cyst rarely occurred after surgical procedures such as bone graft or spine puncture. However, the report of epidermoid cyst associated with flap in the hand is very rare. We experienced such epidermoid cyst after the groin flap mimicking malignancy in the distal phalanx of the thumb. We found calcified mass with bony erosions in radiologic findings and heterotrophic signals and partial necrosis in magnetic resonance imaging that suggested malignancy. However, it was pathologically diagnosed as an epidermoid cyst. Therefore, we report the case and literature review.