Organizing pneumonia associated with Richter transformation in chronic lymphocytic leukemia: a case report and review of the literature.

Organizing pneumonia (OP) is defined histologically by the presence of granulation tissue within alveolar ducts and alveoli. Recently, several lymphoid neoplasms have been implicated as a risk factor for OP, however, OP as a primary manifestation of malignancy transformation has not been widely reported in the literature. Here, we report a case of a patient with a history of chronic lymphocytic leukemia (CLL) who presented with weight loss, low-grade fever, lymphadenopathy, and bilateral pulmonary infiltrates revealed in imaging studies. Video-assisted thoracoscopic lung biopsy showed CLL cells within the pulmonary vessels and areas of OP in the lung parenchyma. Subsequent lymph nodes biopsies were consistent with CLL transformation to diffuse large B-cell lymphoma (DLBCL). To our knowledge, this is the first reported case of OP associated with CLL transformation into DLBCL. This case suggests that OP could represent a form of immunological reaction to ongoing Richter transformation.