Chronic ulcer in a patient with essential thrombocythemia taking hydroxyurea.

Chronic skin ulcers in patients with suspected pyoderma gangrenosum can, on closer inspection and further workup, have a different cause. Recognition of key features on clinical examination such as the presence of atrophie blanche is key to avoid misdiagnosis of pyoderma gangrenosum and its subsequent treatment with high-dose corticosteroids and other immunosuppressive medications.