A 73 year old male presents with enlarged cervical nodes. He has had recurrent infections over the last year. His conjunctiva is pale. Choose the single cell type you will find on the blood film

The key is D. Mature lymphocytes. [Diagnosis is CLL. Chronic lymphocytic leukemia is a type of cancer in which the bone marrow makes too many lymphocytes which looks mature but with defective function. Age of patient is usually above 50 yrs. There is lymhadenopathy and splenomegaly. Recurrent infections points towards abnormal function of lymphocytes against infection. Pale conjunctiva is due to anaemia. This is a blood and bone marrow disease that usually gets worse slowly. Therefore survival rates for chronic lymphocytic leukemia are good compared to many other cancers].