Four cases of cell cannibalism in highly malignant feline and canine tumors

Our plain-English summary of Four cases of cell cannibalism in highly malignant feline and canine tumors, by F.C. Ferreira, M.J. Soares, S. Carvalho, et al (Diagnostic Pathology, 2015).

The study

• Authors: F.C. Ferreira, M.J. Soares, S. Carvalho, L. Borralho, G. Vicente, S. Branco, J. Correia, M.C. Peleteiro
• Journal: Diagnostic Pathology
• Published: 2015;10:199
• Type of article: Case report
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Four cases of tumors in which cell internalization was frequently visualized are reported: one feline mammary carcinoma, one feline cutaneous squamous cell carcinoma, one canine pulmonary squamous cell carcinoma and one canine pleural mesothelioma. Cell internalization was observed by cytology in two of these cases (the feline mammary tumour and the pleural effusion in the canine mesothelioma) and by histopathology in all but the canine mesothelioma. Immunohistochemical staining for pancytokeratin was positive for both internalized and host cells, while E-cadherin expression was frequently absent, although internalized cells occasionally stained positive. This cell-to-cell interaction seems to be associated with tumors displaying a strong epithelial-mesenchymal transitional phenotype, in which cancer cells become engulfed by other cancer cells. Such event could be regarded as an important hallmark of very high malignancy.

In plain English

This was a case report by veterinary pathologists based in Portugal. It described four animal tumors in which, in the authors' words, cell internalization (one cell inside another) was a frequent phenomenon; the authors said this could be classed as cannibalism or entosis. The four were a 9-year-old cat with a mammary carcinoma, a 15-year-old cat with a skin squamous cell carcinoma, a 12-year-old Labrador with a lung squamous cell carcinoma, and an 11-year-old Boxer with a biphasic mesothelioma of the pleura. The article did not mention asbestos or any other cause. Cells inside cells were seen in tissue from the first three tumors. In the dog with mesothelioma they were seen only in the fluid around the lungs. In the first three cases, staining for pancytokeratin was positive in both the engulfing and the engulfed cells. In the two cat tumors, engulfed cells only occasionally stained for E-cadherin. The authors noted that the cells in the mesothelioma fluid might have been mesothelial cells engulfing tumor cells rather than tumor cells engulfing each other. They concluded that the feature seemed associated with tumors showing marked epithelial-mesenchymal transition.

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: case report (four veterinary cases)
• Who was studied: Four animals: a 9-year-old spayed female European shorthair cat (mammary carcinoma), a 15-year-old female cat (skin squamous cell carcinoma), a 12-year-old intact male Labrador (lung squamous cell carcinoma) and an 11-year-old intact female Boxer (pleural mesothelioma). The authors were based in Portugal. No dates were given.
• Exposure: The article does not mention asbestos or any other exposure. It describes tumor tissue and fluid examined by microscopy, cytology and immunohistochemistry.
• Main results:
  • Case 1 (cat, mammary carcinoma): internalized tumor cells were seen in some areas of the primary tumor and also in the lung metastasis.
  • Case 2 (cat, skin squamous cell carcinoma): images of cell internalization were very frequent.
  • Case 3 (dog, lung squamous cell carcinoma): internalization was very frequent at the edge of the lung tumor but was not evident in the metastases.
  • Case 4 (dog, pleural multicystic biphasic mesothelioma): frequent images of cell internalization were present in smears of the pleural effusion. They were not reported in the tumor tissue.
  • Case 4 diagnosis: the mesothelioma had spread through the pleural cavity, with severe pleural effusion.
  • In case 1 the engulfing (cannibalizing) cells stained for E-cadherin, while the internalized cells were only occasionally positive. Case 2 showed the same pattern.
• The authors' conclusion: The authors concluded that this cell-to-cell interaction seems to be associated with tumors that have a strong epithelial-mesenchymal transitional phenotype. They suggested it could be regarded as a hallmark of very high malignancy. They believed it could be classed as cannibalism or as entosis.
• Limitations the authors state:
  • The authors stated that clearly distinguishing cannibalism from entosis was beyond the scope of the work.
  • In the mesothelioma case, the authors stated that the internalizing cells in the pleural fluid could have been mesothelial cells engulfing shed tumor cells, rather than tumor cells engulfing tumor cells.
  • The authors stated that no conclusion could be drawn on whether the internalized cells had functional adherens junctions before being engulfed.

Topics

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

Medical terms in this study, explained in our Lexicon: Carcinoma, Squamous Cell Carcinoma, Pleural Mesothelioma, Cytology, Pleural Effusion, Mesothelioma, Histopathology, Immunohistochemistry.

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