<prompt> Which group of lymph node is classically involved in IMN:Posterior cervicalAnterior cervicalPretrachealSubmandibular  <response>: Ans: a Posterior cervical Ref: Harrison, 16th ed, p. 1046In IMN. the classical group of lymph node involved is posterior cervical nodes.Infectious mononucleosisThe disease is caused by Ebstein -Burr virus EB V, a gamma herpes virus.Saliva is the main means of spread, either by droplet infection or environmental contamination in childhood, or by kissing among adolescents and adults.Clinical features Lymphadenopathy especially posterior cervical Pharyngeal inflammation Fever, non specific skin rash Palatal petechiae Periorbital edema Splenomegaly Clinical or biochemical evidence of hepatitisInvestigation20 or more of the peripheral lymphocytes must have atypical morphology- Characteristic heterophile antibody in serum detected by Paul -Bunnell test or monospot slide test- Specific EBV serology immunoflourescence can be used to confirm the diagnosis.TreatmentAspirin gargles to relieve sore throatIf throat culture yields a haemolytic streptococcus, then erythromycin is prescribedAmoxicillin should be avoided because it causes maculopapular rash in patients with IMN.Note-Diseases caused by EBV virus IMN Nasopharyngeal carcinoma Burkitts Lymphoma Hodgkins Lymphoma B cell Lymphoma Post organ transplant lymphomaHTLV-1- Adult T cell leukaemiaHepatitis C- Lympho plasmacytic lymphomaH.Pylori- Gastric MALT lymphomaHHV-8- Primary effusion lymphoma multicentric Castle mans disease. 