Localized fibrous "mesothelioma" of pleura (submesothelial fibroma): a clinicopathologic study of 18 cases.

Eighteen cases of solid fibrous tumors of the visceral pleura are studied. The series includes neoplasms of various sizes removed during the last 17 years at The Mount Sinai Hospital. Most tumors showed consistent gross and light microscopic features, such as encapsulation, preservation of pedicle, origin from visceral pleura, predominance of spindle cells with more or less hyalinized stroma, little or no pleomorphism or mitotic activity and no infiltration of the underlying lung. No sex predominance or relation to environmental pollutants was noted. Peak incidence was in the 6th decade of life. Total excision proved curative in all cases with no recurrences or complications. The cell of origin of this tumor appears to be a noncommitted mesenchymal cell present in the areolar tissue subjacent to the mesothelial lining.