Upon palpation, the physician noted a strong pulse consistent with a traumatic arteriovenous fistula (in this case involving the superficial temporal artery). This finding, combined with the cyst’s appearance and the patient’s history, led the physician conclude that this was an epidermoid (sebaceous) cyst. (Prior to palpation, the visual differential diagnosis included dermoid cyst, lipoma, trichilemmal or epidermoid cyst, and foreign body granuloma.)
Cystic nodules on the forehead and midline deserve close scrutiny. This author has seen 3 similar cases in 10 years of daily dermatology consultative practice that have involved the superficial temporal artery and a history of head trauma. Each case had been stable for many months before presentation and had been incorrectly identified as a more common benign cyst.
In this particular case, the planned procedure in the outpatient setting was cancelled and the patient was referred to Vascular Surgery, where surgeons were planning to perform a ligation of the superficial temporal artery.
Photos and text for Photo Rounds Friday courtesy of Jonathan Karnes, MD (copyright retained). Dr. Karnes is the medical director of MDFMR Dermatology Services, Augusta, ME.