Cutaneous leiomyosarcoma (LMS) is a rare malignant smooth muscle tumor in dogs and humans, potentially arising from smooth muscle fibers of hair follicles, blood vessels, or genital tissues. This study examined the prevalence, clinicopathological features, hematological changes, and immunohistochemical characteristics of canine cutaneous LMS. Over a 10-year period in Urmia, Iran, six cases (three local and three invasive) of cutaneous leiomyosarcoma (LMS) were identified among 318 dogs presenting with cutaneous lesions representing a prevalence of 1.88%. The hematological analysis indicated significant leukocytosis, monocytosis, and eosinophilia in the affected dogs (p < 0.05) compared to the healthy dogs. Microscopically, a range of cellular pleomorphism and neoplastic smooth muscle fibers in interlacing bundles with scant stromal connective tissue were observed. Immunohistochemistry (negative for MyoD1, Myogenin, and CD31) confirmed piloleiomyosarcoma. A significant increase (p < 0.05) was observed in positive expression and H-score for Desmin, SMA, Vimentin, and Ki67 markers. EGFR and β-Catenin expression was significantly increased in the localized LMS group (p < 0.05) compared to invasive LMS and normal tissue, whereas E-Cadherin expression showed no significant difference in LMS cases. These findings indicate that EGFR is not limited to epithelial tumors but is also expressed in mesenchymal tumors like LMS. The reduction in invasive LMS cases suggests EGFR upregulation may precede metastasis. Although E-Cadherin/β-Catenin expression alone may be insufficient for prognosis, their combined evaluation with proliferative and mesenchymal markers could provide valuable insight into invasion pathways and aid in developing targeted therapies against invasive tumors.
Heydarzadeh et al. (Mon,) studied this question.
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