Pleural involvement in B-cell chronic lymphocytic leukemia associated with a T-cell-rich "reactive" pleural effusion

Because pleural involvement by chronic lymphocytic leukemia (CLL) is virtually impossible to distinguish from inflammatory disorders using cytologic or histopathologic methods, many investigators have relied on immunologic studies of mononuclear cells isolated from lymphocytic pleural effusions to make the distinction. A patient with B-cell CLL is reported in whom pleural involvement was documented using the frozen-section immunoperoxidase technique on a pleural biopsy even though cells isolated from the associated effusion showed only a small polyclonal B-cell population and a predominance of T cells. No other cause for this "reactive" effusion could be identified. The implications of this previously unreported finding of pleural B-cell CLL infiltration associated with a reactive effusion are discussed.