Patterns of chromosomal imbalances in benign solitary fibrous tumours of the pleura

Our plain-English summary of Patterns of chromosomal imbalances in benign solitary fibrous tumours of the pleura, by M. Krismann, H. Adams, M. Jaworska, et al (Virchows Archiv, 2000).

The study

• Authors: M. Krismann, H. Adams, M. Jaworska, K.M. Müller, G. Johnen
• Journal: Virchows Archiv
• Published: 2000;437(3):248-55
• Cited by: 45 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Solitary fibrous tumours (SFTs) of the pleura, in contrast to malignant mesothelioma, occur independently of previous asbestos exposure. They are benign tumours, but may recur if the stalk to the adjacent pleural or lung tissue remains in situ during surgical removal. The molecular pathology of SFTs is largely unknown. We used comparative genomic hybridisation (CGH) to characterise 12 localised SFTs and 12 predominantly sarcomatoid mesotheliomas. Fifty-eight percent of the investigated SFTs did not show any chromosomal imbalances. The most frequent defects were losses on chromosome arms 13q (33%), 4q and 21q (17% each). Significant gains were seen at chromosome 8 and at 15q in two cases each. There was no correlation between tumour size and molecular pathology findings. In contrast, 75% of the mesotheliomas carried chromosomal defects. On average, the mesotheliomas showed over three times as many defects per tumour as the SFTs. Localisation of several frequent losses and gains were similar to those of the SFTs. Therefore, in individual cases, a clear distinction between SFTs and sarcomatoid mesotheliomas is not possible based on CGH analysis alone. Further molecular characterisation of this rare tumour entity will be necessary to elucidate possible genes involved in early tumorigenesis.

In plain English

This laboratory study from the Institute of Pathology in Bochum, Germany, used a technique called comparative genomic hybridisation (CGH) to look for gained or lost chromosome material in tumour tissue. The authors examined 12 benign solitary fibrous tumours of the pleura or mediastinum, chosen from a collection of 32 because their DNA was usable. For comparison they examined 12 malignant sarcomatoid pleural mesotheliomas, all recorded as asbestos associated. Seven of the 12 fibrous tumours (58%) showed no significant chromosomal defects. Their most common defect was a loss on chromosome arm 13q, seen in 33% of these tumours. Only three of the 12 mesotheliomas (25%) had no significant defects detectable by CGH. The mesotheliomas averaged 6.2 defects per case, against 1.8 for the fibrous tumours. Both tumour types shared some defects, at 4q, 8q, 13q and 15q. In the fibrous tumours, defects were not linked to tumour size. Tissue staining (immunohistochemistry) clearly separated the two tumour types. The authors concluded that CGH is of only limited use for telling the two apart, and they cautioned that their numbers were small.

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: Laboratory molecular pathology study of archived tumour tissue, comparing two tumour types using comparative genomic hybridisation (CGH) and immunohistochemistry
• Who was studied: Tumour samples from the files of the Institute of Pathology and the German Mesothelioma Registry, University Clinic Bergmannsheil, Bochum, Germany. There were 12 benign solitary (fibrous pleural) tumours from the pleura or mediastinum, selected from 32 for suitable DNA quality: mean patient age 64.8 years (range 45 to 87), 5 women and 7 men. There were also 12 malignant sarcomatoid pleural mesotheliomas: mean age 64.7 years (range 49 to 77), one woman. No study dates are given.
• Exposure: Asbestos exposure was not itself studied. All 12 sarcomatoid mesotheliomas were recorded as asbestos associated, and two had asbestos body counts of 900 and 2300 asbestos bodies/cm3 lung tissue. No fiber types were reported. No asbestos exposure information was given for the fibrous tumour patients.
• Main results:
  • Seven of the 12 solitary fibrous tumours (58%) had no significant chromosomal defects detectable by CGH.
  • In the fibrous tumours, loss of chromosome arm 13q occurred in 33% of all cases and in 80% of the cases with any detectable defect.
  • In the fibrous tumours, two cases showed a gain of chromosome 8 and another two a gain at 15q22.
  • Only three of the 12 sarcomatoid mesotheliomas (25%) had no significant defects detectable by CGH.
  • Defects per case averaged 1.8 (range 0 to 10) in the fibrous tumours and 6.2 (range 0 to 20) in the sarcomatoid mesotheliomas.
  • Loss of 13q was the most frequent defect in both groups: 33% of the fibrous tumours and 50% of the sarcomatoid mesotheliomas.
  • The two tumour types shared four common aberrations, at chromosome arms 4q, 8q, 13q and 15q.
  • In the fibrous tumours, no relationship between tumour size and severity of genetic alterations was seen: three of five tumours smaller than 10 cm and four of seven larger than 10 cm had no detectable defects.
  • Immunohistochemistry clearly differentiated the fibrous tumours from the sarcomatoid mesotheliomas. Calretinin staining was positive (focally) in five mesotheliomas (42%).
• The authors' conclusion: The authors concluded that CGH is of only limited use for telling solitary fibrous tumours from malignant sarcomatoid mesotheliomas. In their view, a genome with no or minor defects would favour a fibrous tumour diagnosis, and immunohistochemistry appeared preferable for supporting the diagnosis.
• Limitations the authors state:
  • Only five fibrous tumours and nine mesotheliomas showed any defects, so the authors said the results must be interpreted very carefully.
  • The authors said the number of cases was too low to draw conclusions about a typical defect for pleural fibrous tumours.
  • All fibrous tumours were of the typical variant, so chromosomal changes could not be related to transformation into the atypical variant.
  • The authors noted that metaphase preparation quality and possible degradation of DNA from formalin-fixed tissue can influence CGH results.
  • The authors noted that balanced translocations and small copy-number changes cannot be detected using CGH.

Topics

Medical terms in this study, explained in our Lexicon: Pleura, Malignant Mesothelioma, Asbestos Exposure, Pathology, Sarcomatoid, Mesothelioma, Tumorigenesis.

Related studies

• Severe chromosomal aberrations in pleural mesotheliomas with unusual mesodermal features. Comparative genomic hybridization evidence for a mesothelioma subgroup — M. Krismann, K.M. Müller, et al. (2000)
• Solitary fibrous tumour of the pleura: an ultrastructural and immunohistochemical study — S. Keating, G.T. Simon, et al. (1987)
• Solitary benign fibrous tumors of the pleura — M.A. Regal, A.M. Al Rubaish, et al. (2008)
• Solitary fibrous tumour of the pleura: A case report — G. Rakovich, M. Laflamme, et al. (2010)
• Solitary fibrous tumour of the tongue: a case report with immunohistochemical studies — Y. Yamashita, T. Satoh, et al. (2002)
• Solitary fibrous tumor of the pleura. An immunohistochemical, electron microscopic and tissue culture study of a tumor producing insulin-like growth factor I in a patient with hypoglycemia — E.H. Strøm, F. Skjørten, et al. (1991)

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