A case of adenocarcinoma of the bile duct complicating longstanding ulcerative colitis and associated with the rapid onset and growth of multiple seborrheic keratosis (Leser-Trelat sign) and pure red blood cell aplasia is described. This is the first report of a case of the coexistence of the Leser-Trelat sign and pure red blood cell aplasia in a patient with a malignancy. Both manifestations have been doubted as truly paraneoplastic manifestations because of their rarity in clinical medicine. Their co-existence in the present case would support their associaton with malignancy.