LUNG-CARCINOMA MIMICKING MALIGNANT-LYMPHOMA - REPORT OF 3 CASES

Three cases of lung carcinomas with unusual histologic appearances tha t have received little or no comment in the literature are presented. They were initially confused with malignant lymphoma because of a diff use proliferation of relatively monotonous cells simulating large-cell immunoblastic lymphoma. In each case, the possibility of malignant ly mphoma was excluded with confidence after the immunohistochemical stud y (leucocyte common antigen negative and cytokeratins positive), altho ugh with conventional microscopy several foci of cohesive groups of tu mor cells were observed. The tumors were ranked at the clinical stage II or III when they were initially discovered, but all patients died o f disease within 1 year. The present three tumors show an aggressive b ehavior and could be classified into a peculiar variant of 'large cell ' carcinoma. It is necessary for surgical pathologists to have an idea of these variants of lung carcinoma in order to avoid erroneous diagn osis.