A giant epidermal cyst preoperatively diagnosed by core needle biopsy.

Epidermal cysts are common benign cutaneous tumors that usually appear as slowly growing lumps of up to a few centimeters in diameter. They rarely grow >5 cm in diameter and are referred to as giant epidermal cysts. Although soft tissue tumors >5 cm are recommended for imaging examination and biopsy preoperatively, biopsy of giant epidermal cysts has rarely been performed because of the complications that may arise when non-absorbable materials are released from the cyst. Here, I report a case of a giant epidermal cyst in which a core needle biopsy was performed, and the cyst was preoperatively diagnosed. After core needle biopsy, adverse effects that influenced the clinical course did not arise. Clinicians should not hesitate to perform the core needle biopsy, which can mitigate perioperative uncertainty in giant epidermal cysts.