Clinical characteristics, advanced imaging findings, and long-term outcomes in 50 dogs with calvarial multilobular tumor of bone treated with craniectomy

Background Calvarial multilobular tumor of bone (MLTB) in dogs is treated typically by craniectomy. However, long-term outcome data are lacking. Hypothesis/Objectives To describe the clinical features and long-term outcomes of dogs with surgically treated calvarial MLTB. Animals Fifty client-owned dogs with surgically excised, histopathologically confirmed calvarial MLTB. Methods Retrospective case series of surgically resected calvarial MLTB in dogs. Signalment, clinical and imaging findings, surgical technique, complications, histopathological grade, and outcome (survival, progression) were recorded. Kaplan–Meier survival analysis was performed. Possible prognostic factors were evaluated by Cox proportional hazards modeling. Results Most dogs were neurologically normal (33/50; 66%) at presentation. Tumors commonly involved the parietal (30/50; 60%) and frontal (29/50; 58%) bones and venous sinuses (23/50; 46%). Intraoperative complications (11/50; 22%) included hemorrhage and cerebral swelling; postoperative complications (20/50; 40%) included hypotension, seizures, and transient neurological deterioration. Most dogs (31/50; 62%) had grade I tumors, while the remaining had high-grade (17/50; 34% grade II; 2/50 grade III) tumors. High-tumor grade was associated with progression (HR 19.0; 95% CI, 4.1-88.4; P < .001) and cancer-specific death (HR 3.3; 95% CI, 1.1-9.7; P = .03). En bloc resection was associated with reduced progression (HR 0.1; 95% CI, 0.02-0.3; P < .001). Median cancer-specific survival time was 1005 days (range 1-1088 days) with 1 dog alive at 3165 days. Median progression-free interval was 448 days (range 53-1236 days). Conclusions and clinical importance Long survival and progression-free intervals are common. En bloc resection should be attempted and might reduce recurrence.