The 72
mesothelioma-like
tumors of the pleura (MLTP) found among 33 500 autopsy cases collected over more than 30 years are reviewed. MLTP have a worse prognosis than the 106 cases of pleural
mesothelioma autopsied in our institutes with regard to survival time and metastatic spread. In MLTP,
adenocarcinomas predominate with a wide range of histological and cytological variation and prominent development of connective tissue having its origin in the periphery of the lung. These intrapulmonary primary
tumors often fulfill the criteria of pulmonary
scar cancer. Etiologically, there is no correlation between the origin of this
tumor and smoking or exposure to
asbestos. The absence of mucus formation and glandular differentiation, together with the presence of spindle-shaped
carcinoma components and strong mesothelial or stroma proliferation, can make the differential diagnosis between this
tumor type and
mesothelioma difficult. Immunohistological investigations were performed on 11 cases with
antibodies against
intermediate filament proteins, vascular endothelium,
collagen IV, macrophage
antigens,
carcinoembryonic antigen (CEA), LeuM1, and the antibody BerEP4. Our investigation shows that a battery of several
tumor markers, such as
antibodies against LeuM1, CEA, and the antibody BerEP4, as well as staining with
periodic acid/Schiff/
diastase discriminate primary from secondary
pleural neoplasms, whilst
intermediate filament proteins alone are of little diagnostic value.