Infectious Mononucleosis Presenting with Severe Thrombocytopenia, Positive Anti-Platelets Antibodies, and Peripheral Blood Blasts.

Case Report: 18 year old male presents with 2 weeks history of sore throat, fever, and hemoptysis. Physical examination revealed exudative and hemorrhagic tonsillo-pharyngitis, posterior cervical lymphadenopathy, mild splenomegaly, and petechieal rash involving the extremeties and the trunk. On presentation, CBC showed Hgb of 15.5gm/dl, WBCs of 11.8 K/uL, Platelets count of 4 K/uL. Differential count showed lymphocytes of 56%, reactive lymphocytes 1%. Monospot test was positive. CT abdomen confirmed the physical finding of splenomegaly, and showed mild hepatomegaly. Treatment was initiated with pulse methylprednisone 1g/d, and IVIG 1g/kg/day. Both were given for 2 days. One unit of SDP was transfused on days 2, 4, 5. On day 4 platelets count was 6 K/uL. 2–3% blasts were detected on the peripheral smear on days 4 and 5. Bone marrow biopsy and aspiration were done on day 5. They revealed reactive marrow changes with no increase in blasts. Flow cytometry revealed reactive marrow lymphocyte subpopulations and no inrease in immature myeloid cells. Subsequently, EBV serology was reported; EBV capsid IgM and IgG were both positive at >4-fold higher than upper normal limit. In addition, Platelets antibodies were reported positive for IIB/IIIA, IB/IX, and IA/IIA. Platelets count on day 7 was 58 K/uL without platelets transfusion in the previous 24 hours.

Conclusion: Literature review reveals rare cases of Infectious Mononucleosis presenting with severe thrombocytopenia. Most of these cases were treated successfully with steroids and /or IVIG, similarly to ITP. However, no previous association with peripheral blood blasts has been described. Moreover, only two previous reports have described the association between Infectious Mononucleosis and the presence of platelets antibodies but without details of the receptors involved.