Objective: Japanese chronic lymphocytic leukemia (CLL) provides a diagnostic dilemma due to the low incidence and the heterogeneity shown in its morphology and immunophenotype. We clarified the diagnostic problems in Japanese CLL through our retrospective observation.
Methods: Between 2006 and 2011, we found a total of 48 cases with CLL and other indolent B-cell leukemias. We made a diagnosis of true CLL based on clinical, laboratory, immunophenotypic and cytogenetic data.
Results: Among the 48 cases, only 28 cases (58.3%) were diagnosed with true CLL. Morphologic evaluation using a forced-air dried preparation alone is not helpful to distinguish CLL from other indolent B-cell leukemias, including hairy cell leukemia, mantle cell lymphoma, lymphoplasmacytic lymphoma, and splenic marginal zone lymphoma. CLL immunophenotypic score should be more strictly applied in Japan than in Western countries.
Conclusion: Fluorescence in situ hybridization for CCND1/IGH, the presence of leukocytosis and lymphadenopathy at diagnosis, and the morphological evaluation using naturally air dried preparations are important clues to make a correct diagnosis of Japanese CLL.