Primary pulmonary B-cell lymphoma diagnosed by kappa-lambda imaging of broncho-alveolar lavage fluid lymphocytes.

A 69-year-old woman was examined due to abnormal pulmonary shadows on her chest roentgenogram. Although small lymphocyte proliferation was revealed in specimens by transbronchial lung biopsy (TBLB), immunoglobulin light chain restriction could not be seen. We attempted to verify the B-cell clonality by broncho-alveolar lavage (BAL) and a new sensitive method called kappa-lambda imaging (KLI), which was available for the detection of monoclonal B cells. Therefore, B-cell monoclonality was found. Thus, the patient was diagnosed as having primary pulmonary lymphoma (PPL). PPL may be differentiated from benign lymphoproliferative disorders such as pseudolymphoma and lymphocytic interstitial pneumonia by KLI of BAL-derived lymphocytes.