Thrombocytopenic purpura occurring during the early phase of a mumps infection.

Thrombocytopenic purpura with reduced megakaryocyte count in bone marrow was found in a very early phase of a mumps infection in a one year 9 months old boy. No antithrombocyte antibodies were detected. Three weeks later, the mumps antibody titer in the serum was significantly elevated, and thrombocyte and megakaryocyte counts returned to normal.