Primary and metastatic alveolar rhabdomyosarcoma: clinical case reports in canines from the Peruvian Amazon

This report presents four cases of alveolar rhabdomyosarcoma in canines, affecting the striated muscular tissues of the rostral skin, mandible, uterus, and multiple metastases. These cases were treated at veterinary clinics across the San Martín region (provinces of San Martín, Moyobamba, and Tocache), Peru, from a total of 118 neoplastic cases diagnosed histopathologically at the Animal Histopathology Laboratory of the Professional School of Veterinary Medicine, National University of San Martín, between 2020 and 2024. Diagnosing alveolar rhabdomyosarcoma requires a combination of histopathological analysis, immunohistochemical markers, and molecular techniques to distinguish it from other neoplastic variants. These cases highlight the importance of histopathological analysis, appropriate selection of chemotherapy or surgical resection, owner compliance, and the limitations of empirical therapies which, in the absence of a diagnostic foundation, often lead to recurrence and treatment failure in tumor management. In recent years, cytological and histopathological diagnosis has become a key resource in the San Martín region, contributing significantly to therapeutic decision-making and the prognostic evaluation of various types of canine neoplasms.