Hairy Cell Leukemia
This patient with hairy cell leukemia was a 40 y/o male who presented with pancytopenia and splenomegaly. The diagnosis was established by a bone marrow biopsy. Splenectomy specimen showed homogenous dark-brown parenchyma. Sections show a monotonous infiltrate of mononuclear cells in the red pulp. These cells were positive for tartrate-resistant acid phosphatase.