A 65 year old man presents to the clinic complaining of weakness and recurrent infections for 6 months. He has no significant medical, surgical or family history. Physical examination reveals multiple enlarged lymph nodes. Histopathology reveals excessive mature B cells that mark strongly with CD5 and CD23 and weekly with CD22. They also have weak expression of kappa chains on the plasma membrane.
What is the most likely diagnosis?
A- Acute lymphatic leukemia
B- Chronic lymphocytic leukemia
C- Chronic myeloid leukemia
D- Hairy cell leukemia
E- Sezary syndrome
This is a typical case of chronic lymphocytic leukemia. Other leukemias have strong expression of CD22.
The correct answer is B