<prompt> An 8 year old boy presented with fever and bilateral cervical lymphadenopathy with prior history of sore throat. There was no hepatomegaly. The peripheral blood smear shows 20 lympho-plasmacytoid cells. The most likely diagnosis is -InfluenzaTuberculosisInfectious mononucleosisAcute lymphoblastic leukemia  <response>: Ans. is b i.e., Infectious Mononucleosis Infectious mononucleosis Infectious mononucleosis : Is the most characteristic disease produced by Epstein Barr Virus Clinical features : o Most infections are asymptomatic. o Headache, Abdominal pain, chills also seen in few casees. o Fever, malaise, sore throat, exudative pharyngitis, loss of appetite o Generalized lymphadenopathy : Posterior and anterior cervical LN are almost always enlarged. Splenomegaly is found in 50-75 cases while hepatomegaly is found only in 30 cases. o Maculopapular rash. Laboratory findings : a. Atypical Lymphocytosis : Comprising over 10 of total lymphocytes at some time in the illness. b. Paul Bunnel test is positive c. Monospot test is the screening test 