title: Lymphohistiocytoid mesothelioma of the pleura.
abstract: Lymphohistiocytoid mesothelioma (LHM), reported to be a rare variant of sarcomatoid mesothelioma, is challenging to differentiate from non-Hodgkin's lymphoma due to marked lymphocytic infiltration. To aid accurate recognition of LHM, we examined immunohistochemical, in situ hybridization (ISH) of Epstein-Barr virus RNA (EBER-1) mRNA, fluorescence ISH (FISH) for homozygous deletion of 9p21, and asbestos analysis in four cases (three men and 1 woman). Three patients died, while Case 4 was still alive 19 months after extrapleural pneumonectomy. Histologically, these cases were characterized by heavy lymphocytic infiltration. All neoplastic cells were positive for calretinin, AE1/AE3, and epithelial membrane antigen, but negative for CEA. EBER1 factor was negative. FISH analysis demonstrated homozygous deletion of the 9p21 locus in three of the four cases. In Case 1: (i) autopsy findings showed mesothelioma primarily located in the right parietal pleura, but metastasized into the left lung and abdominal organs; (ii) the histological findings at autopsy indicated sarcomatoid mesothelioma; and (iii) we found asbestos bodies and fibers in extracts from lung tissue (Cases 1 & 4) using digestion with bleaching fluid. LHM, an infrequent variant of sarcomatoid mesothelioma, displayed homozygous deletion of the 9p21 locus (three of four cases), and has a relatively favorable prognosis for the sarcomatoid type.
authors.affiliation: Department of Pathology and Laboratory Medicine, National Defense Medical College, Tokorozawa, Japan. tkawai@ndmc.ac.jp
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kawai
authors.forename: Sadayuki
authors.initials: S
authors.lastname: Hiroi
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takagawa
authors.forename: Reiji
authors.initials: R
authors.lastname: Haba
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Hayashi
authors.forename: Kae
authors.initials: K
authors.lastname: Kawachi
authors.forename: Akinori
authors.initials: A
authors.lastname: Nozawa
authors.forename: Akira
authors.initials: A
authors.lastname: Hebisawa
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nakatani
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D005260:Female; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008654:Mesothelioma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008854:Microscopy, Electron; D008875:Middle Aged; D010997:Pleural Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D012367:RNA, Viral