Clinical Relevance of an Extended Diagnostic Work-Out in Patients with Primary Autoimmune Amolytic Anemia (AIHA)

Abstract 3192

Autoimmune hemolytic anemia (AIHA) is a rare disease, with an incidence of 1:100,000 for warm AIHA and of 1:1,000,000 for cold AIHA. AIHA can occur without any evidence of an underlying disorder (idiopathic or primary AIHA) or can be diagnosed in association with another disease (secondary AIHA), such as a malignancy, a lymphoproliferative disorder (LD), an autoimmune disorder, an infection. A successful treatment of secondary AIHA is based upon the treatment of the associated disease. In particular, the detection of a possible underlying LD is a relevant issue since a successful treatment approach for both conditions includes monoclonal antibodies that target B lymphocytes producing the anti-erythrocyte autoantibody (AeAb). With the aim of unravelling the presence of an associated disease, between January 2000 and January 2012, patients with an AIHA diagnosis defined as “primary” on clinical grounds and observed at our institution were included in this study. Patients were required to show anemia, serological evidence of an AeAb by a positive direct antiglobulin test, clinical and laboratory signs of hemolysis, no previous history and/or clinical signs of an associated malignancy, LD, autoimmune disorder, infection or a prior use of drugs commonly implicated in the pathogenesis of AIHA. Before starting treatment, a diagnostic work-out including the following examinations was carried out: autoantibody profile (anti-nucleus; anti-cardiolipin; anti-gastric parietal cells; anti-beta 2-glycoprotein-I; anti-peroxidase and anti-thyroglobulin); HBV, HCV and HIV serology; total body CT scan or chest X-ray associated with an abdomen ultrasound, bone marrow (BM) aspirate and biopsy, peripheral blood (PB) and BM immunophenotype by 4 color flow-cytometry analysis (CD19/CD5/CD3/CD20; CD23/CD10/CD19/CD20; Igκ/Igλ; CD19/CD5; CD3/CD4/CD45/CD8). Sixty-four patients were included in the study, 23 males and 41 females with a median age of 65.5 years (range: 20–83). The median Hb value was 7.9 g/dl (range: 4–11 g/dl), the median value of indirect bilirubin 2.2 mg/dl. The AeAb isotype form was an IgG in 38 cases (59%), IgM in 25 (39%; cold IgM associated with IgG, 4 cases; warm IgM, 1 case) and IgA in 1. After the initial screening, a primary AIHA diagnosis was confirmed in 38 cases (59%), while in 21 patients (33%) an underlying LD was detected, in 2 (3%) a cancer (breast, larynx), in 2 (3%) an autoimmune disorder (Hashimoto's thyroiditis, athrophic gastritis), in 1 an active HCV hepatitis. In the majority of cases (19/21, 90.5%) the diagnosis of LD was made on the basis of the BM biopsy. In all cases with BM involvement, PB flow-cytometry revealed the presence of monoclonal B lymphocytes (median number of clonal lymphocytes, 0.405×10⁹/L) displaying most frequently a lymphoma-like phenotype (CD5−/CD20+/CD23±). As expected, the group of patients with the evidence of a LD included a significantly higher rate of cases with an IgM AeAb as compared to the group with “true” primary AIHA (67% vs 12.5%; p= .005). Taken together, the results of this study demonstrate that in 41% of patients with an AIHA defined as primary on clinical grounds, an extended diagnostic work-out allowed to identify an associated disease, most frequently a LD involving the BM associated with a clonal B population in PB. These data suggest that in patients with a diagnosis of AIHA, an extended screening including a BM biopsy and a PB immunothenotype should be considered in order to identify (or exclude) the presence of a LD and to address the appropriate treatment.