Giant desmosomes in tumors

Our plain-English summary of Giant desmosomes in tumors, by F.N. Ghadially, P.U. Rippstein, S. Cavell, et al (Ultrastructural Pathology, 1995).

The study

• Authors: F.N. Ghadially, P.U. Rippstein, S. Cavell, S.L. Venance
• Journal: Ultrastructural Pathology
• Published: 1995;19(6):469-74
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The lengths of desmosomal profiles were measured in sections of tumor tissue from cases of mesothelioma, adenocarcinoma, squamous cell carcinoma, thymoma, and meningioma. Giant desmosomes (length of profile 1 micron or greater than 1 micron) were found in all the above-mentioned tumors except adenocarcinomas. The largest desmosomal profile in adenocarcinoma was approximately 0.8 micron long; the largest in mesothelioma was approximately 2 microns long. Our observations suggest that one of the ways in which giant desmosomes arise is by growth and fusion of adjacent desmosomes. Giant desmosomes may at times help in distinguishing mesothelioma from adenocarcinoma, but this is a rather rare phenomenon. In this study giant desmosomes were found in only 2 out of 10 cases of mesothelioma.

In plain English

This laboratory study from Ottawa Civic Hospital, Canada, used electron microscopy to measure desmosomes in archived tumor tissue. Desmosomes are small junctions that hold neighbouring cells together. It examined 10 cases each of mesothelioma (9 pleural, 1 peritoneal), adenocarcinoma, squamous cell carcinoma, thymoma and meningioma. Asbestos exposure was not studied. Giant desmosomes, meaning profiles 1 micrometre long or longer, were found in every tumor type except adenocarcinoma. They appeared in 2 of 10 cases each of mesothelioma and squamous cell carcinoma, 3 of 10 thymomas and 1 of 10 meningiomas. In mesothelioma, 12 of 396 measured desmosomes were giant, and the largest in the study series was 2.028 micrometres. An addendum reported a later-found 2.5-micrometre giant desmosome in a mesothelioma. The largest in adenocarcinoma was about 0.8 micrometres. Desmosomes in adenocarcinoma were significantly smaller than those in mesothelioma, squamous cell carcinoma and thymoma. The authors concluded that a giant desmosome would strongly support a diagnosis of mesothelioma rather than adenocarcinoma. Its diagnostic value, they added, is limited because these are rare. They noted that measuring sectioned tissue underestimates true desmosome size.

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 morphometric (measurement) study using electron microscopy of archived tumor tissue blocks
• Who was studied: Tumor tissue from 50 past cases held at Ottawa Civic Hospital, Ontario, Canada: 10 each of mesothelioma (9 pleural, 1 peritoneal), adenocarcinoma, squamous cell carcinoma, thymoma and meningioma. Dates of the cases were not given.
• Exposure: No asbestos or other exposure was studied. The study measured the length of desmosome profiles seen under the electron microscope.
• Main results:
  • Giant desmosomes (1 micrometre or longer) were found in 2 of 10 mesothelioma cases.
  • Giant desmosomes were also found in 2 of 10 squamous cell carcinoma cases, 3 of 10 thymoma cases and 1 of 10 meningioma cases.
  • No giant desmosomes were found in the adenocarcinoma group. The largest desmosome there was about 0.8 micrometres.
  • In the mesothelioma group, 12 of 396 desmosomes measured (3%) were giant.
  • The largest desmosome in the mesothelioma group of the original measured series was 2.028 micrometres.
  • Desmosomes in the adenocarcinoma group were significantly smaller than those in the mesothelioma, squamous cell carcinoma and thymoma groups. They were not significantly different from those in the meningioma group.
  • Desmosomes in thymoma were significantly larger than those in meningioma.
  • The authors interpreted their images as supporting the idea that one way giant desmosomes form is by fusion, or growth and fusion, of neighbouring desmosomes.
  • In an addendum, the authors reported later finding a giant desmosome 2.5 micrometres long in a mesothelioma.
• The authors' conclusion: The authors concluded, drawing on this and earlier work, that when the choice lies between mesothelioma and adenocarcinoma, finding a giant desmosome would strongly support mesothelioma. They also concluded that its diagnostic value is limited because giant desmosomes are rare and are found in only a few mesotheliomas.
• Limitations the authors state:
  • Measuring desmosomes in thin sections underestimates their true size, so the authors stated the figures have no absolute value and are useful only for comparison.
  • The authors said differences between their results and an earlier study may stem partly from the small samples in both studies.
  • Still images cannot show which direction a process is moving in, so the proposed fusion origin of giant desmosomes is an interpretation.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Adenocarcinoma, Squamous Cell Carcinoma.

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• Ultrastructural studies of malignant cells in fluids — G.A. Herrera, J.A. Wilkerson (1985)
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