Aleukemic Leukemia Cutis: An Unusual Rash in a Child

CMAJ • FEBRUARY 9, 2010 • 182(2) © 2010 Canadian Medical Association or its licensors 171 Apreviously healthy four-year-old girl presented with a rash of sudden onset consisting of erythematous macules on both cheeks (Figure 1) that were neither itchy nor tender and did not blanch. Over the next week, the rash spread from her cheeks to her arms, back, thighs and buttocks, and became papular and darker. The patient had no other symptoms. One week later, when the rash had not resolved, oral cephalexin was prescribed. The rash did not improve and the patient was referred to a pediatric dermatologist. A skin biopsy performed two weeks after the onset of the rash showed leukemic blast cells (Figure 2). Bloodwork was then performed and a peripheral blood smear showed blast cells. Physical examination showed hepatosplenomegaly and mild cervical lymphadenopathy in addition to the rash. A complete blood count showed a leukocyte count of 17.7 (normal 5.0–14.5) × 10/L, a hemoglobin level of 115 (normal 115–135) g/L, a platelet count of 175 (normal 150–450) × 10/L, an absolute neutrophil count of 0.35 (normal 1.5–8.0) × 10/L and a blast cell count of 16.6 (normal < 0.01) × 10/L. No evidence was found of tumour lysis syndrome. A bone marrow aspirate confirmed T-cell acute lymphoblastic leukemia with 80%–85% blast cells (Figure 3). Immunophenotyping showed that the blast cells were positive for CD45, CD3, CD7, CD5 and DNA nucleotidylexotransferase. They were also weakly positive for CD79a and CD2. Cytogenetic testing showed a structural rearrangement between chromosomes 9 and 12 resulting in the deletion of their short arms (45,XX,-9,t(9;12)(q12;p1)). The results of a lumbar puncture showed no evidence of leukemic cells. A radiograph of the chest was normal. Ultrasonography of the abdomen confirmed hepatosplenomegaly with extension of the edge of the liver to 3 cm below the costal margin and enlargement of the spleen to a diameter of 13.9 cm. Induction therapy was started immediately, using protocol COG AALL 0434, which includes intrathecal methotrexate, intrathecal cytarabine, vincristine, prednisone, peg-asparaginase and daunorubicin. At the end of induction, the patient’s bone marrow contained 26% blast cells. Remission was achieved during the consolidation phase using nelarabine, cyclophosphamide, cytarabine, mercaptopurine, vincristine, peg-asparginase and intrathecal methotrexate. No complications occurred from the chemotherapy. The rash resolved midway through induction chemotherapy without scarring or residual pigmentation.