What is it?

May-Hegglin anomaly is a rare, inherited, blood platelet disorder characterized by abnormally large and misshapen platelets (giant platelets), neutrophils with abnormal cytoplasmic inclusions and variable thrombocytopenia. The defect of the white blood cells consists of the presence of very small (2-5 micrometers) rods, known as Dohle bodies, in the fluid portion of the cell (cytoplasm). Some people with May-Hegglin anomaly may have no symptoms while others may have various bleeding abnormalities. In mild cases, treatment for May-Hegglin anomaly is not usually necessary. In more severe cases, transfusions of blood platelets may be necessary.

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Additional names

This group contains additional names:
- May Hegglin anomaly

Signs & symptoms

Some people with May-Hegglin anomaly may have symptoms at birth while others may have no symptoms throughout their lifetime. Symptoms may include red or purple colored spots on the skin (purpura), nose bleeds (epitaxis), excessive bleeding from the mouth during dental work, headaches, and/or muscle weakness on one side of the body due to bleeding within the brain (intracranial bleeding).
Excessive bleeding may occur in some people with May-Hegglin anomaly when steroid drugs used to treat another disorder are discontinued.


The diagnosis of May-Hegglin anomaly is made by specialized blood tests that reveal giant, oddly shaped platelets and characteristic cellular "inclusions" in certain white blood cells (leukocytes). The presence of inclusion bodies in leukocytes helps to distinguish May-Hegglin anomaly from immune-mediated thrombocytopenia. There also might be fewer platelets than normal (mild thrombocytopenia). Immunofluorescence study of neutrophil NMMHC-IIA can be helpful for diagnosis of May-Hegglin anomaly in patients without leukocyte inclusion bodies. Genetic studies for MYH9 gene mutation can confirm the diagnosis of May-Hegglin anomaly in uncertain cases. A comprehensive molecular evaluation includes a screening of 40 exons. It is hypothesized that genetic assessment can evaluate the risk of development of cataracts, deafness and kidney disease but this is debatable.


The literature is conflicting, but most patients with May-Hegglin anomaly do not appear to have clinically significant bleeding problems, and specific treatment is not required. Corticosteroids and splenectomy are ineffective. In rare patients with severe bleeding, platelet transfusion may be required.
Patients with May-Hegglin anomaly who undergo normal vaginal or cesarean delivery do not appear to have a significantly increased risk of bleeding.
For patients with May-Hegglin anomaly scheduled for surgery, a careful personal and family history of bleeding tendency should be obtained and a manual platelet count performed to determine the actual risk for bleeding. Intravenous desmopressin acetate (DDAVP) may be valuable. A patient with May-Hegglin anomaly who successfully underwent craniotomy after desmopressin acetate infusion alone has been described 10. Routine prophylactic platelet transfusions are not usually indicated, though it is prudent to ensure that platelets are available in case unexpected bleeding occurs.
Depending on the degree of thrombocytopenia and family history, individuals may be at an increased risk for bleeding, and refraining from participation in contact or collision sports may be prudent.
A hematologist should be consulted to assist in the management of patients who are undergoing surgery or vaginal delivery and patients who have experienced severe trauma.

☝️ This is not a substitute for professional medical advice. Please consult with your physician before making any medical decision.

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