title: Expression of the KIT protein (CD117) in primary cutaneous mast cell tumors of the dog.
abstract: Thirty-one canine cutaneous masses, diagnosed as mast cell tumors (MCT) by histopathologic analysis, were used to evaluate the immunohistochemical pattern of expression of KIT protein (CD117), a type III tyrosine kinase protein involved in mast cell growth and differentiation. Lesions were graded as I (well differentiated), II (intermediate differentiation), or III (poorly differentiated) according to the following morphologic features: invasiveness, cellularity and cellular morphology, mitotic index, and stromal reaction. Immunohistochemical KIT expression was compared with histologic grade and some histomorphologic features (cell differentiation and nuclear grade) evaluated separately. A possible predictive role of biologic behavior in MCTs for KIT expression was also investigated. Immunohistochemical analysis revealed three different patterns of KIT expression: a cytoplasmic diffuse pattern, a membranous pattern with immunostaining located on the cell surface, and a cytoplasmic perinuclear pattern, where KIT expression was detected in the cytoplasm of the neoplastic mast cells, close to the nucleus. Statistical analysis showed a close relationship between different KIT immunohistochemical patterns and histologic grade (P < 0.00000), cell differentiation (P < 0.00000), and nuclear grade (P < 0.0024). According to Kaplan-Meier-estimated survival curves compared by survival analysis, KIT expression was significantly associated with survival time (P = 0.037) but not cancer-free interval (P = 0.50). Similar to other well-known histomorphological features, KIT expression is a useful parameter of malignancy in cutaneous MCTs. KIT expression also predicted the biological behavior of the tumors in this study.
authors.affiliation: Department of Veterinary Public Health and Animal Pathology, Ozzano Emilia, Bologna, Italy.
authors.forename: Rosario
authors.initials: R
authors.lastname: Preziosi
authors.forename: Maria
authors.initials: M
authors.lastname: Morini
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Sarli
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D004283:Dog Diseases / Q000378:metabolism* / Q000473:pathology; D004285:Dogs; D005260:Female; D015870:Gene Expression / Q000235:genetics*; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D012515:Mast-Cell Sarcoma / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D009361:Neoplasm Invasiveness; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*
chemical_list: D019009:Proto-Oncogene Proteins c-kit