Hematopathology Case 03

2-Year Old Male with Numerous Infections, Persistent Leukocytosis and Monocytosis

Jolanta Jedrzkiewicz, MD

Pathology Resident, University of Utah School of Medicine

Editor: Mohamed Salama, MD

Medical Director, Hematopathology, ARUP Laboratories,
Associate Professor (Clinical) of Pathology, University of Utah School of Medicine

The patient is a 2 year old male who initially presented with easy bruising, petechiae, numerous infections and developmental and speech delay/regression. Further evaluation demonstrated persistent thrombocytopenia, anemia, and leukocytosis with absolute monocytosis. He was initially treated for idiopathic thrombocytopenic purpura ITP but his clinical status continued to worsen. He had negative radiology / imaging studies and normal metabolic disease panels. He developed generalized lymphadenopathy and hepatosplenomegaly, which led to bone marrow and liver biopsies.

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Pathology Findings:

  • Peripheral blood smear demonstrated leukocytosis with absolute monocytosis, circulating blasts/ blast equivalents (6%), anemia, thrombocytopenia and granulocytic left shift (fig. 1) (fig. 2) (fig. 3) .
    WBC:27.89 K/MCLRBC:4.02 M/µL
    HGB:9.0 G/DLHCT:31.5%
    MCV:78.4 FLMCH:22.4 PG
    MCHC:28.6 G/DLRDW:18.9%
    PLT:59 K/MCL
  • Differential Count (100 cells): Bands 6%, segmented neutrophils 3%, lymphocytes 19%, monocytes 55%, eosinophils 1%, metamyelocytes 2%, myelocytes 8% and blasts 6%, 11 NRBC's per 100 WBC's.

  • Bone marrow biopsy showed normocellular marrow with trilineage hematopoiesis and normal megakaryocytes. The aspirate specimen revealed monocytosis of 16.6%, normal blast count and elevated myeloid to erythroid ratio (M:E) at 3.7 (normal range: 1.1-3.5), consistent with myeloid proliferation (fig. 4) (fig. 5) (fig. 6) .

  • Liver biopsy showed periportal mixed inflammatory infiltrate mainly consisting of myeloid precursors, lymphocytes and monocytes on morphology. Immunohistochemical stains were not performed (fig. 7) (fig. 8) . Additional findings included marked periportal steatosis and patchy sinusoidal fibrosis.

  • The hemoglobin F was elevated at 11.3% (normal: 0.2-2%).

  • Flow cytometry performed on bone marrow showed monocytosis (23% of total leukocytes) with mature immunophenotype and no aberrant expression of antigens. Additional findings included normal blast count 1% and no other abnormalities.

  • Cytogenetic studies showed normal male karyotype, 46, XY.

  • Molecular testing: KRAS (c.35G>A (pGly12Asp) mutation was detected on a specialized panel.

Final Diagnosis & Discussion

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