Plasmacytoid Lymphocytes: A Diagnostic clue to Dengue Infection

Introduction Dengue fever is the most common arboviral disease in world and present cyclically in tropical and subtropical regions. The four serotypes of dengue virus 1, 2, 3, 4 come under subgroup of Flavivirus ( Group B arboviruses). Dengue is now becoming a commonest vector borne infection in India. Clinical diagnosis can be difficult as its presenting signs and symptoms are easily confused with malaria, typhoid and other non specific viral infections. In developing countries like India where huge population is being endemic and resources are limited, early and effective assessment of CBC and PBF can be very helpful in patient management. Material and method A cross sectional study was carried out on a series of patients presenting with High grade fever, bodyache and lethargy. CBC and PBF were first performed for every patient. Those having thrombocytopenia and atypical plamacytoid lymphocytes were further analysed by Dengue rapid card test for NS1 Ag and IgM antibody. Results Out of 150 patients, 50 were found dengue positive by Either Ns1 Ag or IgM antibody. All 50 patients showed atypical plasmacytoid lymphocytes on PBF examination. Conclusion Raised hematocrit, Leucopenia with relative lymphocytosis, thrombocytopenia and presence of plasmacytoid lymphocytes ( greater than10 % of total lymphocytes) was consistent finding and gives an important diagnostic clue for dengue.