Canine cutaneous perivascular wall tumors (cPWT) at first presentation : clinical behaviour and prognostic factors on 55 cases

Abstract Background – Canine Cutaneous Perivascular Wall Tumors (c-PWT) are soft tissue sarcomas recently identified when hemangiopericytomas were reclassified. No previous clinical data are available for c-PWT. Hypothesis/Objectives – To define the clinical behavior and prognostic role of clinical and pathological variables in a homogeneous population of c-PWT. Animals – Fifty-five c-PWT, in 53 client-owned dogs at first presentation undergoing surgery. Methods – Retrospective case series. The endpoint was the relapse of tumor (local and/or distant). The prognostic values of clinical (age, sex, weight, site and tumor size, adjuvant therapy) and pathological (status of surgical margins, histologic grade, mitosis, percentage of tumor necrosis) variables were investigated by univariate and bivariate analysis (P<0.05). The pattern of associations between variables was explored by multivariate correspondence analysis (MCA). Results – Twelve dogs had a relapse. Ten dogs had local recurrence, 1 had metastatic disease and 1 had both. The estimated probability of local recurrence was 0.02, 0.08, 0.20 e 0.24 at 6 months, 1, 2 and 3 years, respectively. Size of the tumor was a significant prognostic factor while status of margins had only a clinically relevant Hazard Ratio. In MCA evaluation, young age, tumor size (< 5 cm), grade I and location in the extremities were associated. Association was observed also for older age, tumor size (>5 cm), grade II and other location. Conclusion and clinical importance – C-PWT tend to locally recur long time after surgery. An early diagnosis of c-PWT associated with small tumor size (<5cm) and clean surgical margins ensures a good prognosis independently of histological grade.