Pure Red Cell Aplasia in Follicular Lymphoma with Bone Marrow Involvement and Isoniazid Exposure.

Pure red cell aplasia is a rare bone marrow failure syndrome that is often overlooked, as it is potentially associated with other more common diseases. This report describes a 79-year-old man who was referred due to red cell transfusion-dependent anemia, severe reticulocytopenia, and generalized lymphadenopathies. An excisional lymph node biopsy suggested a diagnosis of follicular lymphoma. Trephine biopsy identified areas of lymphoma infiltration and a significant reduction of erythroid precursor cells. The patient was treated with four-weekly doses of rituximab; however, only after suspension of isoniazid treatment for latent tuberculosis was a complete and persistent hematologic recovery achieved. This case highlights the rarely described association between pure red cell aplasia and isoniazid in a patient with simultaneous follicular lymphoma with bone marrow involvement. Recognition of such connections is crucial for accurate diagnosis and appropriate management, as the treatment of lymphoma might not be sufficient as a sole strategy for clinical improvement.