Typing of intermediate filaments in malignant fibrous pleural tumors

Abstract

We report two cases of a malignant fibrous pleural tumor, one of the localized type and one of the diffuse type. In both cases, typing of intermediate filaments by immunofluorescence microscopy showed that the tumor cells were positive for vimentin and negative for (cyto)keratin and desmin. This result supports the concept that malignant fibrous pleural tumors do not arise from the (cyto)keratin-positive pleural mesothelium but from the submesothelial fibrous tissue. Thus, instead of the usual term "malignant fibrous mesothelioma", the term "malignant submesothelial fibrosarcoma" should be preferred.

Pleural mesothelioma of connective tissue type, localized fibrous tumour of the pleura, and reactive submesothelial hyperplasia. An immunohistochemical comparison

“…For example, it has been reported that cytokeratin is limited t o the surface mesothelial cells of the pleura and that the submesothelial cells fail to stain for this epithelial marker. 6 More recently, however, it has been suggested that in reactive states submesothelial cells that normally lack cytokeratin acquire this marker as they pr~liferate.~*~** We have sought to confirm or refute these conflicting reports by applying antibodies raised against vimentin and cytokeratin intermediate filaments to mesotheliomas of connective tissue type and reactive pleural conditions. At the same time, we have applied the same antibodies to localized fibrous tumours of the pleura, as this should provide information relevant to histogenesis as well as to diagnosis.…”