While the majority of canine osteosarcomas (OSA) arise from the medullary cavity, a subset arises from the surface of bone. In humans, surface OSA often has a more indolent disease course with better outcomes than medullary OSA. The aim of this retrospective case series was to evaluate the clinical outcome and potential prognostic factors of dogs with surface OSA. Medical records from 11 dogs previously diagnosed with surface OSA were included. Histopathology of cases was evaluated during case review by two veterinary anatomic pathologists. Median progression free interval (PFI) and overall median survival time (OST) were estimated using Kaplan–Meier methods. Intergroup comparisons were performed using log-rank tests. Six dogs were diagnosed with periosteal OSA, 4 dogs with parosteal OSA, and one dog with an unclassified surface OSA. Two dogs were found to have metastatic disease at the time of diagnosis and four developed metastatic lesions after treatment. The median PFI and median OST for all dogs with surface OSA was 425 and 555 days, respectively. The 6 dogs diagnosed with periosteal OSA had a median PFI of 461 days and median OST of 555 days, while the 4 dogs with parosteal OSA had a PFI of 350 days and the OST could not be calculated. Multiple prognostic factors (surgery, systemic adjunctive therapy, elevated alkaline phosphatase at diagnosis, appendicular vs axial location, mitotic count, and tumour grade) were evaluated and none were prognostic for PFI or OST. Dogs with surface OSA appear to have prolonged PFI and OST, consistent with humans with surface OSA.

中文翻译：

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11例犬表面骨肉瘤的回顾性分析

虽然大多数犬骨肉瘤 (OSA) 起源于髓腔，但也有一小部分起源于骨表面。在人类中，表面 OSA 通常比髓质 OSA 具有更惰性的病程，但结果更好。本回顾性病例系列的目的是评估患有表面 OSA 的狗的临床结果和潜在的预后因素。其中包括 11 只先前被诊断患有表面 OSA 的狗的医疗记录。在病例审查过程中，两名兽医解剖病理学家对病例的组织病理学进行了评估。使用 Kaplan-Meier 方法估计中位无进展间期 (PFI) 和总中位生存时间 (OST)。使用对数秩检验进行组间比较。六只狗被诊断患有骨膜 OSA，四只狗患有骨旁 OSA，一只狗患有未分类的表面 OSA。两只狗在诊断时被发现患有转移性疾病，四只狗在治疗后出现转移性病变。所有患有表面 OSA 的狗的中位 PFI 和中位 OST 分别为 425 天和 555 天。诊断为骨膜性 OSA 的 6 只狗的中位 PFI 为 461 天，中位 OST 为 555 天，而 4 只患有骨膜旁 OSA 的狗的 PFI 为 350 天，无法计算 OST。对多种预后因素（手术、全身辅助治疗、诊断时碱性磷酸酶升高、阑尾与轴向位置、有丝分裂计数和肿瘤分级）进行了评估，但没有一个因素是 PFI 或 OST 的预后因素。患有表面 OSA 的狗似乎有较长的 PFI 和 OST，与患有表面 OSA 的人类一致。