<prompt> A 17 years old female presents with sore throat, lymphadenopathy and positive heterophile antibodies test. Diagnosis is ?TuberculosisStreptococcal pharyngitisInfectious mononucleosisCytomegalic inclusion disease  <response>: Ans. is c i.e., Infectious mononucleosis Laboratory diagnosis In IMN, there is predominantly lymphocytosis with presence of 20 or more atypical lymphocytes. These atypical lymphocytes are activated T-lymphocytes which have round or irregularly shaped nuclei, with abundant flowing cytoplasm that characteristically has a dark-staining peripheri. 