Malignant mesothelioma with a pronounced myxoid stroma: a clinical and pathological evaluation of 19 cases

Our plain-English summary of Malignant mesothelioma with a pronounced myxoid stroma: a clinical and pathological evaluation of 19 cases, by J. Shia, J. Qin, R.A. Erlandson, et al (Virchows Archiv, 2005).

The study

• Authors: J. Shia, J. Qin, R.A. Erlandson, R. King, P. Illei, J. Nobrega, D. Yao, D.S. Klimstra
• Journal: Virchows Archiv
• Published: 2005;447(5):828-34
• Cited by: 29 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Mesothelioma with a pronounced myxoid stroma has been identified as a morphological pattern that might portend a better prognosis. Reports on this type of cases are few. Its clinical and pathological features are not defined. In this study, we identified 19 such cases from a series of 234 pleural mesotheliomas and performed a comprehensive clinical and pathological analysis. The inclusion criteria were mesotheliomas with at least 50% of the tumor exhibiting a pronounced myxoid stroma that occupied more than 50% of the tumor volume (designated as myxoid mesothelioma). There were ten males and nine females, with a median age of 58 years. Forty seven percent of the patients had probable or definite asbestos exposure. Patients presented at various stages [International Mesothelioma Interest Group (IMIG) stage II, 4; stage III, 9; and stage IV, 6]. Most (16/19) patients were treated by extrapleural pneumonectomy with adjuvant radiation or chemotherapy or both. Overall, the median survival rate was 36 months (median follow-up time, 17 months), and the 2-year survival rate was 79%. Histologically, the tumor cell component was entirely epithelioid without significant cytologic atypia. The myxoid material stained positive for Alcian blue, and the staining diminished after treatment with hyaluronidase in 12 of 12 cases. The tumor cells showed a typical mesothelial immunophenotype. Ultrastructurally, all six tumors examined had typical mesothelial-type surface microvilli and a moderately electron-dense extracellular amorphous material that often formed a haze enmeshing the surface microvilli. Hyaluronic acid-type, fern-like crystals were noted in all cases. These findings show that myxoid mesotheliomas represent a group of epithelioid mesotheliomas that have retained the secretory activity of normal mesothelium. Patients may present at different stages, but survival appears to be superior to that of epithelioid mesotheliomas in general. Our study emphasizes the need for better attention to histologic subtypes, particularly in the context of prognostically or therapeutically oriented investigations of this lethal disease.

In plain English

This study reviewed pleural mesothelioma cases treated at Memorial Sloan-Kettering Cancer Center from 1993 to 2001. Of 234 cases with tissue available, 19 (8%) met the authors' definition of myxoid mesothelioma: at least half the tumor contained pronounced myxoid (mucus-like) stroma filling over half of those areas. The 19 patients were ten men and nine women, aged 40 to 75. Asbestos exposure was confirmed in six, suggested in three, not identified in nine and unknown in one. Sixteen had extrapleural pneumonectomy (removal of the lung and its lining). Two who died of heart attacks within a month of surgery were excluded from survival analysis. Among the other 17, median survival was 36 months (median follow-up 17 months), and estimated 2-year survival was 79%, with a 95% confidence interval printed as 0.601 to 1.00. All tumors were epithelioid. In all 12 cases tested, pretreatment with the enzyme hyaluronidase neutralized the stroma's Alcian blue stain. The authors concluded their findings seem to suggest a survival advantage. They noted the small case number and the lack of proper controls for stage and treatment, and called for further studies.

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 and pathological case series drawn from one hospital's files. It used pathology review, immunohistochemistry, electron microscopy and Kaplan-Meier survival analysis, and had no comparison group.
• Who was studied: 234 pleural mesothelioma cases with tissue available, treated at Memorial Sloan-Kettering Cancer Center, New York, between 1993 and 2001. Of these, 19 met the myxoid criteria: 10 males and 9 females aged 40 to 75, with 14 right-sided and 5 left-sided tumors.
• Exposure: The study examined a tumor subtype, not an exposure. Each patient's asbestos exposure history was recorded, but no fiber types, products, jobs or doses were reported.
• Main results:
  • Myxoid mesothelioma was defined as at least 50% of the tumor containing pronounced myxoid stroma that occupied more than 50% of the tumor volume in those regions. 19 of the 234 pleural mesothelioma cases (8%) met this definition.
  • Among the 19 patients, ages ranged from 40 to 75 years, with a median of 58 and a mean of 59.8.
  • Among the 19 patients, asbestos exposure was confirmed in 6 (32%) and suggested in 3 (16%). No exposure was identified in 9, and the information was unavailable for 1.
  • At presentation, 6 patients had IMIG stage IV disease, 9 had stage III and 4 had stage II.
  • 16 of the 19 patients underwent extrapleural pneumonectomy, some with added radiation and/or chemotherapy.
  • At last follow-up (range 1 to 75 months), 6 patients had died of disease 4 to 65 months after diagnosis.
  • The two patients who died of myocardial infarction within 1 month of surgery were excluded from survival analysis, leaving 17 patients. Among these 17, median overall survival was 36 months, with a median follow-up of 17 months.
  • Among the 17 patients analysed, estimated 2-year overall survival was 79% (95% CI 0.601 to 1.00) and estimated 3-year overall survival was 35% (95% CI 0.127 to 0.972).
  • In all cases, the tumor cells were epithelioid and showed no significant cytologic atypia. No case showed sarcomatoid features.
  • In all 12 cases tested, the myxoid stroma stained positive with Alcian blue at pH 2.5, and pretreatment with hyaluronidase neutralized this staining.
  • Among the 12 cases tested, the Ki-67 proliferation index was less than 5% in 7 cases and 10 to 30% in 5.
  • Electron microscopy was performed in 6 cases. All 6 showed mesothelial-type surface microvilli and fern-like material similar in appearance to hyaluronic acid crystals.
• The authors' conclusion: The authors concluded that myxoid mesotheliomas are a group of epithelioid mesotheliomas that have retained the secretory activity of normal mesothelium, and that their findings seem to suggest a survival advantage for these patients.
• Limitations the authors state:
  • The number of cases was small, and there were no proper controls for stage and treatment.
  • The sample was too small to compare outcomes between patients with less than 5% Ki-67 labeling and those with more.
  • Further studies are needed to confirm the survival advantage.

Topics

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

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Myxoid Stroma, Mesothelioma, Prognosis, Pleural Mesothelioma, Asbestos Exposure, IMIG, Extrapleural Pneumonectomy (EPP).

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