Autoimmune cytopenia is observed in many hematological malignancies, whereas immune thrombocytopenia is rarely observed in plasma cell dyscrasias, such as multiple myeloma. On the other hand, cytopenias secondary to myelosuppression due to lenalidomide use are frequently observed, whereas immune thrombocytopenia is a rarer complication.

A 63-year-old female patient without any known disease was performed bone marrow biopsy in January 2019 due to anemia and high sedimentation rate. She was diagnosed with IgG-kappa type multiple myeloma and administered four cycles of bortezomib-cyclophosphamide-dexamethasone treatment. She went into remission after this treament and was then performed autologous stem cell transplantation followed by a consolidation therapy comprising 2 cycles of bortezomib-lenalidomide-dexamethasone treatment. Subsequently, she was administered lenalidomide maintenance therapy with regular follow-up visits. Isolated thrombocytopenia was observed in the patient in her last follow-up visit and was therefore hospitalized for further examination. No schistocyte was observed in the peripheral smear as well as no rouleaux formation. It was determined that her LDH (lactate dehydrogenase) levels were normal and that she did not have organomegaly. The results of the Coombs test, in addition to the results of hepatitis B, hepatitis C, HIV (Human Immunodeficiency Virus), EBV (Ebstein-Barr Virus), and ANA (antinuclear antibody) tests, which were run in order to determine whether she had any viral diseases, came out as negative. Post-transfusion purpura was ruled out in the patient as she had no history of transfusion in the last three months. She was then performed bone marrow biopsy, since her platelet count did not increase after discontinuation of lenalidomide treatment despite the fact that she was given platelet suspension transfusion. Subsequently, it was was determined that her megakaryocyte count increased, whereas her plasma cell ratio was less than 5%. In view of the foregoing, she was pre-diagnosed with lenalidomide-related immune thrombocytopenia, and was thus given 1 gr of methylprednisolone for 3 days followed by the administration of methylprednisolone at a daily dose of 1 mg/kg for 5 days. However, a sufficient increase in her platelet count could not be achieved with the said treatment. Therefore, she was administered eltrombopag therapy instead, since she was refractory to other treatments that could have been administered as a replacement treatment, such as IVIG (Intravenous Immunoglobulin), rituximab or cyclophosphamide. The patient, whose platelet count increased after the administration of eltrombopag therapy, was then discharged with full recovery.

The aim of this case report is to demonstrate that lenalidomide-associated immune thrombocytopenia should also be considered when there is isolated thrombocytopenia in patients with multiple myeloma without a decrease in other cell lines.