A young man’s yellow leg ulcer has served as a lesson in considering differential and albeit unusual diagnoses after US dermatologists discovered it was caused by sickle cell disease.

The 21-year-old patient presented to ED at the Baylor University Medical Center in Houston, Texas, with a “rapidly progressive, exquisitely painful ulcer” with yellow slough on his right leg.

The round, indurated ulcer had appeared two weeks prior but had failed to improve when he applied topical antibacterial fusidic acid.

He had been taking hydroxyurea and folic acid to manage his sickle cell disease for eight years and had arrived in the US from Yemen one week before the ulcer appeared.