Answer is C (CLL) Incidental finding of Lymphocytosis (80,000/mcL) in an elderly and asymptomatic patient suggests the diagnosis of CLL. Why is CLL the single best answer of choice here ? 'CLL is a disease of older patients wth 90% of cases occurring after the age of 50 years and median age of presentation is 65 years'. - CMDT The patient in question is aged 80 years and hence falls in the bracket of CLL. 'Typical B cell CLL is often fbund incidentally when a complete blood count is done for another reason'. -Harrison 16th / 648 The patient in question is asymptomatic and the findings represent incidental observation on a full blood count done for an obscure reason. 'The hallmark of CLL is absolute lymphocytosis. White cell count is usually greater than 20,000/mcL may be markedly elevated to several 100,000/mcL. Usually 75-80% of circulating cells are lymphocytes'. - CMDT The patient in question is presenting with a white cell count of 100,000/mcL and 80% of circulating cells are lymphocytes. This finding is consistent with the blood picture of CLL.