Sarcomatoid mesothelioma: a clinical-pathologic correlation of 326 cases

Our plain-English summary of Sarcomatoid mesothelioma: a clinical-pathologic correlation of 326 cases, by S. Klebe, N.A. Brownlee, A. Mahar, et al (Modern Pathology, 2010).

The study

• Authors: S. Klebe, N.A. Brownlee, A. Mahar, J.L. Burchette, T.A. Sporn, R.T. Vollmer, V.L. Roggli
• Journal: Modern Pathology
• Published: 2010;23(3):470-9
• Cited by: 104 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Sarcomatoid mesothelioma is the least common, but most aggressive of the three major histological types of mesotheliomas. This study comprises 326 cases of sarcomatoid mesotheliomas among 2000 consecutive malignant mesothelioma cases received in consultation (16%). Patients included 312 men (96%) and 14 women (4%), with a median age of 70 years (range 41-94 years). Most tumors were pleural (319; 98%), and 7 were peritoneal (2%). Some desmoplastic features were identified in 110 cases (34%), and 70 (21%) were classified as desmoplastic. Rare subtypes included two cases with a lymphohistiocytoid pattern (<1%) and eight heterologous mesotheliomas (2%). Labeling for cytokeratins (CKs) was observed in 261/280 cases (93%), and for calretinin and vimentin in 31 and 91%, respectively. Pleural plaques were present in 79% of cases for which information was available, and asbestosis was diagnosed in 34/127 cases (27%). Median survival was 3.5 months. Fiber analysis was performed in 61 cases. The median asbestos body count was 1640/g wet lung tissue (by light microscopy). Amosite fibers were the most commonly identified fibers using energy-dispersive X-ray analysis and were significantly higher in the sarcomatoid cases, as were uncoated fibers using scanning electron microscopy. This study represents the largest series of sarcomatoid and desmoplastic malignant mesotheliomas to date and confirms the diagnostic usefulness of CK immunohistochemistry. The relationship with asbestos exposure--particularly amosite--and an association with pleural plaques and less often asbestosis is confirmed.

In plain English

This study reviewed 326 cases of sarcomatoid mesothelioma. They were 16% of 2000 consecutive mesothelioma cases, mostly professional and medicolegal consultations, in one author's database. Patients were 312 men and 14 women, median age 70. In all, 319 tumors were pleural and 7 peritoneal. Tumor cells stained for cytokeratins in 261 of 280 cases tested and for calretinin in 12 of 39. Pleural plaques were found in 144 of 182 patients, asbestosis in 34 of 127. Lung fiber analysis in 61 cases found elevated asbestos content in 57. Their median asbestos body count (1640 per gram of wet lung) exceeded that of other mesothelioma types (348), a difference not statistically significant. Among fiber types, only amosite concentration was significantly higher, and amosite was the most common fiber found. Among 260 patients with survival data (follow-up 1 to 22 months), about 10% were alive at one year; 3.5-month survival was called median in the abstract, mean in a figure legend. The authors concluded that the study confirms the usefulness of cytokeratin staining and a relationship with asbestos exposure, particularly amosite.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective clinical-pathologic case series of consultation cases from one researcher's database, with lung fiber analysis in a subset
• Who was studied: 326 patients with sarcomatoid mesothelioma (including desmoplastic, lymphohistiocytoid and heterologous subtypes) among 2000 consecutive mesothelioma cases, mainly professional and medicolegal consultations, collected over about 25 years. There were 312 men (96%) and 14 women (4%), median age 70 years (range 41 to 94). In all, 319 tumors (98%) were pleural and 7 (2%) peritoneal.
• Exposure: Asbestos content of lung tissue in 61 cases: asbestos bodies by light microscopy, and uncoated fibers typed by electron microscopy and energy-dispersive X-ray analysis. Fibers were grouped as commercial amphiboles (amosite and crocidolite), non-commercial amphiboles (tremolite, anthophyllite, actinolite) and chrysotile. Results were compared with non-sarcomatoid mesotheliomas and with a reference population of non-asbestos-exposed individuals. Pleural plaques and asbestosis were also recorded.
• Main results:
  • Subtypes among the 326 sarcomatoid cases: the text reports 70 (21%) classified as desmoplastic and some desmoplastic features in 110 (34%). Table 1 gives different figures (see text problems).
  • Cytokeratin staining was positive in 261 of 280 sarcomatoid cases tested (93%).
  • Calretinin was positive in 12 of 39 cases tested (31%), often only focally. Vimentin was positive in 101 of 111 (91%).
  • Pleural plaques were present in 144 of 182 patients with information (79%).
  • Histological asbestosis was found in 34 of 127 patients (27%).
  • In 57 of the 61 sarcomatoid cases with fiber analysis (93%), asbestos content was elevated, exceeding the reference population.
  • In sarcomatoid cases, the median asbestos body count was 1640 per gram of wet lung (range less than 3 to 436 000). In non-sarcomatoid mesotheliomas it was 348 (range less than 0.2 to 1.6 million). The difference was not statistically significant (P = 0.07). The reference population median was 2.9.
  • Commercial amphiboles (amosite plus crocidolite): median 15 600 fibers per gram in sarcomatoid cases versus 6640 in non-sarcomatoid tumors; the reference population median was less than 600. Amosite concentrations were significantly higher in the sarcomatoid group (P = 0.03).
  • Amosite was the most common fiber type identified.
  • Non-commercial amphiboles (tremolite, anthophyllite, actinolite): median 4180 fibers per gram in sarcomatoid cases versus 2540 in non-sarcomatoid cases. The difference was not significant (P greater than 0.05).
  • Chrysotile: median 1450 fibers per gram in sarcomatoid cases versus 1100 in other mesothelioma types (P greater than 0.7).
  • Survival data were available for 260 of 326 patients (80%), with follow-up of 1 to 22 months. Among these patients, about 70% were alive at 2 months, 50% at 4 months, 30% at 6 months, 10% at 1 year and 5% at 18 months.
  • Survival of 3.5 months was reported: as the median in the abstract, and as the mean in the Figure 5 legend.
• The authors' conclusion: The authors concluded that the study confirms the diagnostic usefulness of cytokeratin immunohistochemistry. They also concluded that it confirms a relationship with asbestos exposure, particularly amosite, and an association with pleural plaques and, less often, asbestosis.
• Limitations the authors state:
  • The authors stated that their experience with the markers WT1, podoplanin and CK5/6 was too limited to report.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma, Peritoneal mesothelioma.

Medical terms in this study, explained in our Lexicon: Sarcomatoid, Mesothelioma, Malignant Mesothelioma, Desmoplastic Mesothelioma, Lymphohistiocytoid, Calretinin, Pleural Plaques, Median Survival.

Related studies

• Sarcomatoid Peritoneal Mesothelioma: Clinicopathologic Correlation of 13 Cases — E.N. Pavlisko, V.L. Roggli (2015)
• Malignant mesothelioma with heterologous elements: clinicopathological correlation of 27 cases and literature review — S. Klebe, A. Mahar, et al. (2008)
• Sarcomatoid Mesothelioma: A CDKN2A molecular analysis of 53 cases with immunohistochemical correlation with BAP1 — M. Zaleski, N. Kalhor, et al. (2020)
• Epithelioid sarcoma. A clinical and pathologic study of nine cases — H. Santiago, L.K. Feinerman, et al. (1972)
• The differential diagnosis between pleural sarcomatoid mesothelioma and spindle cell/pleomorphic (sarcomatoid) carcinomas of the lung: evidence-based guidelines from the International Mesothelioma Panel and the MESOPATH National Reference Center — A.M. Marchevsky, N. LeStang, et al. (2017)
• Complete pathological response to neoadjuvant pemetrexed/cisplatin in combination with regional hyperthermia in a patient with sarcomatoid peritoneal mesothelioma — S. Kruger, M.K. Angele, et al. (2014)

Browse more research in Modern Pathology, or return to medical research.