Clinico-Hematological Profile of Paroxysmal Nocturnal Hemoglobinuria in Indian Patients: FLAER Flow Cytometry Based Experience from an Indian Tertiary Care Centre.

PNH is a rare disease with wide spectrum of intra-vascular hemolysis and thrombosis to sub-clinical PNH clones. We aimed to study the clinico-hematological profile and clone size on granulocytes and monocytes of PNH patients classified as per International PNH Interest Group recommendations. A retrospective analysis of clinico-hematological profile of 112 PNH clone positive patients by FLAER based flow cytometry between January and September 2017 done and classified into classical PNH, PNH with aplastic anemia or myelodysplastic syndrome (PNH-AA/MDS) and sub-clinical PNH clones (PNH-sc). Of 112 patients, majority were PNH-sc (62) followed by PNH-AA/MDS (34) and classical PNH (16). The commonest clinical feature was anemia in all 3 groups followed by jaundice (87.5%) in classical PNH and fever in PNH-AA/MDS (64.7%) and PNH-sc (48.4%). Thrombosis was present in 25% (4/16) classical PNH and 2.9% (1/34) of PNH-AA/MDS. The mean hemoglobin, reticulocyte count and LDH was higher in classical PNH. Bone marrow was predominantly hypercellular in classical PNH (11/16) and hypocellular in PNH-AA/MDS (31/34) and PNH-sc (50/62) with dyserythropoiesis predominantly in PNH-AA/MDS (83.8%) and PNH-sc (74.1%). Marrow iron was reduced in 62.2% classical PNH contrary to increased in PNH-BMF (58%) and PNH-sc (91%). The mean clone size in PNH-sc was significantly lower with > 50% in 16.2% patients. Three patients with MDS-MLD and MDS-MLD-RS in PNH-sc had > 80% clone on granulocytes and monocytes. Most PNH patients in Indian setting are PNH-sc with significantly lower clone, however, a clone size > 50% is not uncommon in Indian PNH-sc.