Autoimmune hemolytic anemias (AIHA) are rare disorders where autoantibodies destroy self-red blood cells. AIHA includes warm AIHA (wAIHA), cold AIHA (cAIHA or cold agglutinin disease), mixed AIHA (mAIHA), paroxysmal cold hemoglobinuria (PCH), and atypical AIHA (aAIHA) based on direct antiglobulin test (DAT) results. We studied bone marrow features and their link to disease outcomes in AIHA cases with bone marrow trephine biopsies during the disease course.

AIHA patients, who had bone marrow aspiration and trephine biopsy between 2005-2023, were assessed retrospectively. Data included demographics, baseline/follow-up laboratory results (HB, hematocrit, reticulocyte count/percentage, corrected reticulocyte, lactate dehydrogenase, bilirubin, haptoglobin levels, DAT results), bone marrow features (cellularity, erythroid hyperplasia, dyserythropoiesis, marrow reticulin fibrosis, lymphoid infiltrates), treatment details, response, and outcomes.

A total of 43 AIHA patients were studied (32 females), with the median age at diagnosis of 55 years. Patients with grade≥1 MF received more treatment lines (p=0.012). Reticulocytosis was less frequent in ≥MF1 group (p=0.03). Grade 0-1 MF and grade≥2 MF had no difference in treatment response (p=0.089, p=0.055); grade≥2 MF had less frequent reticulocytosis than grade 0-1 MF (p=0.024). Dyserythropoiesis had no impact on treatment or relapse (p=1, p=0.453).MF grade didn't affect relapse (p=0.503).

Our study provides valuable insights into the relationship between bone marrow characteristics and treatment response in AIHA patients. The findings indicate a significant correlation between the degree of MF and a decrease in bone marrow reticulocyte response. Additionally, as the degree of MF increased, the number of treatment lines also increased, suggesting a potential impact on disease progression and management.