title: Four cases of cell cannibalism in highly malignant feline and canine tumors.
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.
authors.affiliation: CIISA, Interdisciplinary Centre of Research in Animal Health, Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477, Lisbon, Portugal. fernandof@fmv.ulisboa.pt.
authors.forename: Fernando Costa
authors.initials: FC
authors.lastname: Ferreira
authors.affiliation: CIISA, Interdisciplinary Centre of Research in Animal Health, Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477, Lisbon, Portugal. mariajsoares@gmail.com.
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Soares
authors.affiliation: CIISA, Interdisciplinary Centre of Research in Animal Health, Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477, Lisbon, Portugal. sancarva@gmail.com.
authors.forename: Sandra
authors.initials: S
authors.lastname: Carvalho
authors.affiliation: Clinica Veterinária do Oriente, Rua Nova dos Mercadores, 13 R/C Dto. 1990-176, Lisboa, Portugal. vetoriente@sapo.pt.
authors.forename: Liliana
authors.initials: L
authors.lastname: Borralho
authors.affiliation: Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477, Lisboa, Portugal. gonvic@sapo.pt.
authors.forename: Gonçalo
authors.initials: G
authors.lastname: Vicente
authors.affiliation: ICAAM - Institute for Mediterranean Agrarian and Environmental Sciences, University of Evora, Mitra, Ap. 94, 7006-554, Evora, Portugal. smmb@uevora.pt.
authors.forename: Sandra
authors.initials: S
authors.lastname: Branco
authors.affiliation: CIISA, Interdisciplinary Centre of Research in Animal Health, Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477, Lisbon, Portugal. jcorreia@fmv.ulisboa.pt.
authors.forename: Jorge
authors.initials: J
authors.lastname: Correia
authors.affiliation: CIISA, Interdisciplinary Centre of Research in Animal Health, Faculdade de Medicina Veterinária, Universidade de Lisboa, Av. da Universidade Técnica, 1300-477, Lisbon, Portugal. mcpelet@fmv.ulisboa.pt.
authors.forename: Maria Conceição
authors.initials: MC
authors.lastname: Peleteiro
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D015820:Cadherins / Q000032:analysis; D002294:Carcinoma, Squamous Cell / Q000737:chemistry / Q000473:pathology / Q000662:veterinary*; D002371:Cat Diseases / Q000473:pathology*; D002415:Cats; D057899:Cytophagocytosis; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005260:Female; D007150:Immunohistochemistry; D007633:Keratins / Q000032:analysis; D008175:Lung Neoplasms / Q000737:chemistry / Q000473:pathology / Q000662:veterinary*; D008297:Male; D015674:Mammary Neoplasms, Animal / Q000737:chemistry / Q000473:pathology*; D008654:Mesothelioma / Q000737:chemistry / Q000473:pathology / Q000662:veterinary*; D010997:Pleural Neoplasms / Q000737:chemistry / Q000473:pathology / Q000662:veterinary*; D012878:Skin Neoplasms / Q000737:chemistry / Q000473:pathology / Q000662:veterinary*
chemical_list: D014408:Biomarkers, Tumor; D015820:Cadherins; D007633:Keratins