Diagnosis of Suspected Precursor-Targeted Immune-Mediated Anemia (PIMA) in a Cat with Prolonged Anemia: A Case Report

The immune-mediated destruction of erythroid precursors within the bone marrow can result in inefficient erythropoiesis, classified as precursor-targeted immune-mediated anemia (PIMA). Herein, we describe the case of a 1-year-old Scottish Fold cat who presented with a pale mucous membrane with a history of prior diagnosis with immune-mediated hemolytic anemia (IMHA), characterized by normocytic normochromic moderate anemia. The cat was administered six months of immunosuppressive therapy, including prednisolone, cyclosporine, or mycophenolate mofetil, but exhibited insufficient reticulocytosis. Bone marrow examination subsequently revealed a decreased myeloid to erythroid ratio of 0.35:1, and PIMA was diagnosed. Treatment modification with chlorambucil was implemented, and the cat remained well-managed without IMHA recurrence for 15 months. This case highlights the importance of careful evaluation methods, such as reviewing medication history and performing bone marrow examinations, in IMHA patients with an insufficient response to immunosuppressive therapy. These results further suggest the occasional need for medication adjustments during treatment.