Anaplastic diffuse large B-cell lymphoma cytologically diagnosed in pleural effusion: Report of two cases

Diffuse large B-cell lymphoma (DLBCL) has some rare special subtypes. Anaplastic variant has the immunophenotypic and genotypic features of DLBCL, and is characterized by the presence of large bizarre hallmark-like and Reed-Sternberg-Hodgkin-like cells. Lymphoblastic lymphoma and DLBCL, non-otherwise specified are the most common lymphoma effusions in adults. Lymphomas in effusion fluids usually show a homogenous uniform population of either small, medium or large cells depending on lymphoma types. Anaplastic pleomorphic lymphoid cells in pleural effusions are not common cytologic findings. Effusions due to lymphomas with large bizarre anaplastic cells, such as anaplastic large cell lymphoma and Hodgkin lymphomas, are rare. Presence of anaplastic cells in effusion fluid is diagnostically challenging. They may be confused with nonlymphoid malignancies. Certain cytomorphologic features are helpful clues. Ancillary immunocytochemistry is a useful confirmatory tool in doubtful cases. We report two cases of anaplastic variant-DLBCL (ADLBCL) cytologically diagnosed in elderly female patients with bilateral pleural effusions. Cytologic examination of effusion fluids showed predominantly medium-large mononuclear uniform cells intermixed with frequent large pleomorphic mononuclear and binucleated cells, and bizarre multinucleated giant cells. Background showed karyorrhexis and absent mixed inflammatory infiltrates. A panel of immunocytochemistry markers in cell block sections confirmed B-cell phenotype of the neoplastic and anaplastic cells. Lymph node biopsy supplemented with immunohistochemistry confirmed the cytologic diagnosis. Even though the presence of anaplastic cells may be confused with other malignancies, cytopathologists should consider ADLBCL in the differential diagnosis of lymphomas with large pleomorphic cells, look for certain cytomorphologic clues and implement an appropriate immunocytochemistry panel.