Clonality of primary pulmonary lymphoproliferative disorders; Using in situ hybridization and polymerase chain reaction for immunoglobulin

Primary pulmonary lymphoproliferative disorders (PLDs) are histologically d ivided into a neoplastic state of high and low grade malignant lymphoma (ML ), and a reactive state of follicular bronchitis/ bronchiolitis (FB) and ly mphoid interstitial pneumonia (LIP). We reviewed 19 cases with PLDs, includ ing 4 cases each of high and low grade B cell ML, 6 FB cases, and 5 cases o f LIP. To clarify the clonality of the proliferating cells, we performed an immunohistochemical examination (IHC), in situ hybridization (ISH) for the immunoglobulin light chain and a polymerase chain reaction (PCR) analysis of the immunoglobulin heavy chain gene using DNA obtained from paraffin sec tions. In addition, a Southern blot analysis was also performed in 6 cases using fresh materials. In MC, all ML were positive for L26 (CD20), while th e monoclonality of the kappa light chain was observed in only one high grad e case. However, using ISH we could detect the clonality in three of four h igh grade ML cases and in one of four low grade ML cases. In FB and LIP, no clonality of immunoglobulin by ISH was observed. In a PCR analysis for the immunoglobulin heavy chain gene, we could detect one or two prominent band s in all 8 cases of high and low grade ML. On the other hand, in all cases of FB and LIP, we could only detect either an oligoclonal or polyclonal pop ulation. In summary, the presence of monoclonality of ISH and/or PCR for th e immunoglobulin heavy chain gene were limited in the neoplastic state, but not in the reactive state.