Secondary Lymphoid Tissues ›› Spleen ›› Abnormal Hairy Cell Leukemia* Click Here for Full Size › Microscopic Features: Peripheral blood smear shows abnormal intermediate-sized lymphocytes with hair-like cytoplasmic projections Prominent nucleolus › Normal % blood-PB, marrow-BM, lymphoid tissue-LN: PB: None BM: None LN: None › May Resemble: Splenic Marginal Zone Lymphoma Reactive lymphocyte CLL › Differential Diagnoses: Splenic Marginal Zone Lymphoma Reactive Lymphocytosis CLL › Classic Immunophenotype: CD19+ CD20+ CD5- CD10- CD103+ CD11c+ CD25+ Annexin1+ › Cartoon Image: Click and drag for direct comparison › Misc: Splenomegaly, Pancytopenia (many with monocytopenia), and dry aspirate during biopsy (due to marrow fibrosis) are common findings The neoplastic cells typically involve the red pulp area of the spleen (as opposed to Splenic Marginal Zone Lymphoma which involves the white pulp)