<prompt> A patient of more than 70 years, presented with generalized lymphadenopathy. WBC count was 20,000 mm3 and blood film showed 70 mature looking lymphocytes. Next investigation that should be doneLN biopsyPeripheral ImmunophenotypingBone marrow aspirationPeripheral blood cytogenetics  <response>: Ans. b. Peripheral Immunophenotyping A patient of more than 70 years, presented with generalized lymphadenopathy. WBC count was 20,000mm3 and blood film showed 70 mature looking lymphocytes. This clinical situation is suggestive of CLL Harrison says Differential diagnosis of typical B cell CLL is extensive. Immunophenotyping will eliminate the other T-cell disorders and can often help so other B-cell malignancies. 