title: Malignant pleural mesothelioma: clinicopathology of 16 extrapleural pneumonectomy patients with special reference to early stage features.
abstract: The earliest pathological events in the development of malignant pleural mesothelioma (MPM) are not understood. The aim of the present study was to elucidate the early histopathological features of MPM. A total of 16 extrapleural MPM pneumonectomy patients were investigated. Early stage mesothelioma was arbitrarily defined as a tumor < or =5 mm in thickness regardless of the nodal status or other organ involvement. Eight of these patients (six with epithelioid, two with biphasic) had early stage mesothelioma by this definition. Macroscopically there was no visible tumor, but the parietal and visceral pleura were thickened and there was focal adhesion between them. Microscopically, the mesothelioma lesions were multifocal and discontinuous on the pleura. In extremely early cases of epithelioid mesothelioma, tumor cells were generally arrayed in a single layer, but papillary proliferation was observed elsewhere. In sarcomatoid mesothelioma, mesothelioma cells proliferated, forming multiple small polypoid nodules on the pleura. Epithelial membrane antigen was helpful to distinguish reactive from neoplastic mesothelium, but glucose transporter-1 was not. Mesothelioma cells disseminate diffusely throughout the parietal and visceral pleura and mediastinal fat tissue before becoming visible. Stage Ia mesothelioma (neoplasm limited to the parietal pleura) would not be observed in daily practice.
authors.affiliation: Department of Diagnostic Pathology, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, Japan. kenzo@faculty.chiba-u.jp
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hiroshima
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Yusa
authors.forename: Toru
authors.initials: T
authors.lastname: Kameya
authors.forename: Ichiro
authors.initials: I
authors.lastname: Ito
authors.forename: Kou
authors.initials: K
authors.lastname: Kaneko
authors.forename: Chikabumi
authors.initials: C
authors.lastname: Kadoyama
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Kishi
authors.forename: Yukio
authors.initials: Y
authors.lastname: Saitoh
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ozaki
authors.forename: Makiko
authors.initials: M
authors.lastname: Itami
authors.forename: Takekazu
authors.initials: T
authors.lastname: Iwata
authors.forename: Akira
authors.initials: A
authors.lastname: Iyoda
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kawai
authors.forename: Ichiro
authors.initials: I
authors.lastname: Yoshino
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nakatani
mesh_terms: D000328:Adult; D000368:Aged; D001194:Asbestos / Q000009:adverse effects; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008654:Mesothelioma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods; D010997:Pleural Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D011013:Pneumonectomy
chemical_list: D001194:Asbestos