Chronic Urticaria as a Presenting Sign of Hairy Cell Leukemia

Chronic urticaria is a common clinical disorder that is idiopathic in over 75% of cases. Less commonly, urticaria may be the presenting manifestation of an allergic or infectious disease, endocrinopathy, inherited syndrome, or autoimmune disorder. Rarely, urticaria may be a sign of underlying malignancy, including leukemia. C.C. is a 48-year-old white female who was referred for evaluation of recurrent urticaria for 3 years. The pruritic, erythematous wheals were pinpoint, and appeared to be precipitated by heat, stress, and effort. Prick tests were negative except to D. pteronyssinus. CBCs over the past 5 years revealed WBCs of 2,300–5,000 cells/mm³. Skin biopsy revealed interstitial edema with infiltration of eosinophils and mast cells consistent with urticaria. The impression was probable cholinergic urticaria, for which hydroxyzine was prescribed with fair symptomatic control. One year later, she presented with bright red blood per rectum. Repeat physical examination revealed lymphadenopathy and splenomegaly. Subsequent laboratory studies showed pancytopenia. Endoscopy was normal except for small, nonbleeding hemorrhoids. Bone marrow biopsy revealed histologic evidence of hairy cell leukemia that was treated with 2-chlorodeoxyadenosine. Upon initiation of chemotherapy her pruritus and urticaria subsided. Recent CBC revealed Hgb 9.2 g/dL, platelets 290,000 cells/mm³, and WBC 4,100 cells/mm³. Peripheral blood smear showed no hairy cells.