PULMONARY B-CELL NON-HODGKINS-LYMPHOMAS - THE VALUE OF IMMUNOHISTOCHEMISTRY AND GENE ANALYSIS IN DIAGNOSIS

We reviewed 45 pulmonary B-cell non-Hodgkin's lymphomas to determine w hether their morphology and immunohistochemical features were those of lymphomas arising from mucosa-associated lymphoid tissue (MALT), as d escribed in other sites, The polymerase chain reaction was used to pro vide further information on clonality, We found that these lymphomas i nfiltrate the pulmonary interstitium along bronchovascular bundles and interlobular septa, subsequently spilling out into airspaces and fina lly destroying the alveolar architecture of the lung. Central hyaline sclerosis and vascular infiltration were common features. All lymphoma s stained CD20 positive and were accompanied by variable numbers of re active CD3 positive T-cells, Cytokeratin staining with CAM 5.2 was use ful in identifying lymphoepithelial lesions. CD21 staining of follicul ar dendritic cells revealed germinal centres where they were not recog nizable on H and E staining. The polymerase chain reaction was perform ed on paraffin tissue from 28 patients. Twenty were low grade, of whic h 12 showed a clonal band and eight showed a polyclonal smear pattern. Eight were high grade, of which one revealed a clonal band, Three pro duced polyclonal smear patterns and four cases were inadequate samples , In one patient who had lymphoma at a second extranodal site, identic al bands were identified, evidence for 'homing' of lymphoid cells towa rds mucosal epithelium.