Cushing's syndrome is accompanied by many different skin symptoms. A case of a 43-year-old female patient with unrecognized adrenocorticotropic hormone (ACTH)-dependent Cushing syndrome is reported. Besides numerous skin lesions, the patient presented with a rapidly progressive leg ulcer due to venous thrombosis. The initial skin symptoms appeared on her lower leg one month prior to admission. The patient was treated with oral prednisone, however, rapid progression of the skin lesion was observed. On admission the patient presented with a large, very painful ulceration, partially covered with a crust, on the right lower leg with several satellite smaller ulcerations. The other leg showed no changes. Moreover, the patient had pronounced hirsutism and skin darkening on the face, and Muehrcke's lines were observed on all her nails. Microscopic findings of skin biopsy were uncharacteristic, with some signs of angiopathy and vasculitis. Based on the elevated serum levels of ACTH and cortisol, and the result of dexamethasone suppression test, ACTH-dependent Cushing syndrome was diagnosed. Sonography of leg veins revealed a recanalized thrombus of the right popliteal vein with reflux. The patient was transferred to surgical department where both suprarenal glands were removed. Upon suprarenal gland removal, significant improvement of the patient's general condition and rapid healing of the leg ulcer were observed. Briefly, this patient is presented to point out that a leg ulcer caused by venous insufficency may mimic fulminant purpura or some other type of vasculitis in patients with Cushing syndrome.