PB1310 - May-Hegglin Anomaly: are giant platelets a giant problem?

Background: A 62-year-old male presented to the Hematology clinic for evaluation of chronic thrombocytopenia. He had a history of bloody stools after periods of constipation and microscopic hematuria, but no other bleeding. He has a cataract from retinal detachment. CBC showed a platelet count of 60 K/uL with giant platelets and Dohle inclusion bodies.

Aims: May-Hegglin Anomaly (MHA) is a rare, autosomal dominant disorder characterized by thrombocytopenia and giant platelets with basophilic inclusion bodies. Mutated MYH-9 (non-muscle myosin heavy chain) gene on chromosome 22q12-13 leads to pathogenic MYH-9 expression and is responsible for what was once thought to be distinct entities of May-Hegglin Anomaly, Fechner, Epstein and Sebastian Syndromes but now are unified under MYH9-related diseases. MHA can be associated with sensorineural hearing loss, cataracts and glomerulonephritis.

Methods: The diagnosis is made upon review of the peripheral blood smear, where cytoplasmic inclusions similar to Dohle bodies may be seen in neutrophils, monocytes, eosinophils and basophils, but not in platelets.

Results: The platelet count may be underestimated due to the presence of macrothrombocytes. Platelet aggregation studies are generally normal and bleeding time is prolonged relative to the degree of thrombocytopenia. Immunofluorescence can aid the diagnosis if inclusion bodies are not visualized.

Conclusion(s): As the spontaneous bleeding tendency associated with MHA is generally mild, the patient was advised to avoid NSAIDS and monitor for bleeding. He was given guidance in regards to any planned procedures and surgeries and was recommended to have CBC performed prior to any invasive procedure to guide platelet transfusion. The use of DDAVP was considered but has not yet been required due to non-severe thrombocytopenia.