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تسجيل

Juvenile Myelomonocytic Leukemia: Laboratory Manifestations

المؤلف:  Hoffman, R., Benz, E. J., Silberstein, L. E., Heslop, H., Weitz, J., & Salama, M. E.

المصدر:  Hematology : Basic Principles and Practice

الجزء والصفحة:  8th E , P1041-1042

2026-11-12

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Laboratory abnormalities may include an elevated white blood cell count with absolute monocytosis, anemia, and thrombocytopenia (Figs. 1 and 2). Monocytes, either circulating in the peripheral blood or in the BM, frequently appear dysplastic. The peripheral smear shows leukoerythroblastic changes, and there are often circulating nucleated red blood cells. Fifty percent of patients may also present with elevated fetal hemoglobin levels and hypergammaglobulinemia, which is of interest given that there are patients recently described with autoimmune lymphoproliferative syndromes who also harbor RAS mutations. International criteria mandate that the BM have fewer than 20% blast cells at diagnosis. Other findings typical in the BM may include micromegakaryocytes.

Fig1. JUVENILE MYELOMONOCYTIC LEUKEMIA: BLOOD, BONE MARROW, LUNG, AND SPLEEN. The illustrations are from the case of a 3-year-old boy who was diagnosed with neurofibromatosis at birth. At 1 year of age, he presented with leukocytosis (58 K/μL). The peripheral blood (A and B) showed left-shifted granulocytes and increased monocytes (16%). A bone marrow biopsy (C and D) was hypercellular as a result of increased granulocytic and monocytic cells that could also be appreciated on the aspirate (E). Blasts accounted for only 4% of the bone marrow elements. A combined esterase reaction (F) illustrated the increased monocytes (α-naphthol butyrate esterase reaction positive; orange/brown) in the background of granulocytes (chloroacetate esterase reaction positive; blue). Cytogenetic analysis revealed monosomy 7. At age 2 years, the patient presented with respiratory distress, and a lung biopsy (G and H) demonstrated a monocyte infiltrate (lysozyme stain, I) consistent with involvement by juvenile myelomonocytic leukemia. This is not uncommon in such patients. At age 3 years, his blast count began to rise, and he underwent a splenectomy (which showed a marked infiltrate of immature and mature monocytes and granulocytic cells [J and K; lysozyme stain, L]). After the splenectomy the patient underwent a successful stem cell transplant.

Fig2. JUVENILE MYELOMONOCYTIC LEUKEMIA: SKIN AND GASTROINTESTINAL TRACT. Patients with juvenile myelomonocytic leukemia sometimes present with or develop skin nodules, which on biopsy show a myelomonocytic infiltrate in the upper and lower dermis (A). Involvement can also be seen in the gastrointestinal tract (B). (The case was kindly provided by Dr. Elizabeth Hyjek, University of Chicago.)