Color Atlas of Hematology - Practical Microscopic and Clinical ...

80Abnormalities of the White Cell Series“Monocytoid” cells with a wide layer of only faintly staining cytoplasmoccur in blood in marginal zone lymphadenoma (differential diagnosis:lymphoplasmacytic immunocytoma).Lymphoma, Usually with Splenomegaly(e.g., Hairy Cell Leukemia and Splenic Lymphomawith Villous Lymphocytes)Hairy cell leukemia (HCL). In cases of slowly progressive general malaisewith isolated splenomegaly and pancytopenia revealed by CBC (leukocytopenia,anemia, and thrombocytopenia), the predominating mononuclearcells deserve particular attention. The nucleus is oval, often kidney beanshaped,and shows a delicate, elaborate chromatin structure. The cytoplasmis basophilic and stains slightly gray. Long, very thin cytoplasmicprocesses give the cells the hairy appearance that gave rise to the term“hairy cell leukemia” used in the international literature. The disease affectsthe spleen, liver, and bone marrow. Severe lymphoma is usually absent.Aside from the typical hairy cells with their long, thin processes,there are also cells with a smooth plasma membrane, similar to cells in immunocytoma.A variant shows well-defined nucleoli (HCL-V, hairy cellleukemia variant). A bone marrow aspirate often does not yield materialfor an analysis (“punctio sicca” or “empty tap”) because the marrow is veryfibrous. Apart from the bone marrow histology, advanced cell diagnosticsare therefore very important, in particular in the determination of bloodcell surface markers (immunophenotyping). This analysis reveals CD 103and 11 c as specific markers and has largely replaced the test for tartrateresistantacid phosphatase.Splenic lymphoma with villous lymphocytes (SLVL). This lymphatic systemdisease mostly affects the spleen. There is little involvement of the bonemarrow and no involvement of the lymph nodes. The blood contains lymphaticcells, which resemble hairy cells. However, the “hairs,” i.e., cytoplasmicprocesses, are thicker and mostly restricted to one area at the cellpole, and the CD 103 marker is absent.Splenomegaly may develop in all non-Hodgkin lymphomas. In hairy cellleukemia, the rare splenic lymphadenoma with villous lymphocytes(SLVL) and marginal zone lymphadenoma may be seen. These mostly affectthe spleen.