Clinical and flow cytometric analysis of paroxysmal nocturnal hemoglobinuria in Indian patients

Abstract

INTRODUCTION: Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon disease. Many cases go undiagnosed as high index of clinical suspicion is required for its detection. This study was performed to detect the presence of PNH defect by flow cytometric immunophenotyping (FCMI) in patients with suspected PNH disease and evaluate their clinical and laboratory profile. MATERIALS AND METHODS: In this retrospective study, a total of 136 patients with suspected PNH who fulfilled the inclusion criteria for the study were evaluated for PNH defect by FCMI using monoclonal antibodies against CD55 and CD59 on red blood cell, granulocytes, and monocytes. RESULTS: Forty-eight (35.3%) of 136 patients evaluated had a PNH defect. Nineteen (39.5%) of these 48 patients had classical PNH (hemolytic type). The remaining 29 patients had PNH Clone in association with aplastic anemia. The clinical and laboratory data of these 19 patients with classical PNH were analyzed in this retrospective study. The median age was 34 years (range: 19–65 years). Thrombotic events were observed in 3 (16%) of the 19 cases (one each with Budd–Chiari syndrome, cerebral venous thrombosis, and abdominal vein thrombosis). The flow cytometric data of these patients were further analyzed for the presence of and size of PNH clone on erythrocytes, granulocytes, and monocytes. PNH clone was detected in 84% of erythrocytes, 76.9 % of monocytes and in 100% granulocytes. CONCLUSION: Classical PNH is not rare in India as previously thought. A high index of clinical suspicions and evaluation by FCMI is necessary for its detection. CD59 is a better marker for identification of PNH clone than CD55 in all three cell types.