Peripheral Blood Smear: A Clue to MYH9-Related Disorder

Excerpt

An 11-year-old boy presented with severe thrombocytopenia. There was no history of bleeding or fever. Complete blood count showed hemoglobin-10.8 g/dl; TLC 5.54 × 10³/cu.mm; platelet count of 20 × 10³/cu.mm; MPV of 9.5 fl (reference interval: 6.5–10 f) and ESR of 15 mm/1st h. Immunologic tests showed normal Anti DS DNA: 7.2 U/ml, Anti Cardiolipin Ab: 1.5 U/ml, and ANA: 0.2 (Negative result less than 1.0) and CRP (< 0.3 mg/dl). Review of Peripheral Blood Smear (PBS) revealed giant platelets with large blue intracytoplasmic inclusions in periphery of the cytoplasm of WBC series (Fig. 1). No toxic change or left shift was seen in the peripheral smear. The findings were suggestive of May–Hegglin anomaly. Similar finding was seen in the PBS of the patient's father. Molecular testing for confirmation could not be done. The morphology was persistent during 2 years by checking every 6 months interval. Döhle body like inclusions within neutrophils are highly suggestive of MYH-9-related disorders. MYH-9-related disorder is a rare autosomal dominant macrothrombocytopenia syndrome which was previously classified as May–Hegglin anomaly with subtypes of Sebastian, Fechtner and Epstein syndromes [1]. Misdiagnosis with immune thrombocytopenia often leads to inappropriate administration of immunosuppressive and steroid therapy [2]. Evaluation of the PBS for giant platelets and Döhle body-like inclusions in the granulocytic series is important for correct diagnosis of this condition.

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