A 9-year-old female neutered Labrador retriever with a swelling on the dorsal skull.

The patient was evaluated by her rDVM on 13/8/2018 for a skull swelling that had grown rapidly over the last 2 weeks with associated discomfort. Radiographs showed a mass associated with the right frontal sinus. She was started on carprofen and referred to the internal medicine service for further workup. A skull CT and biopsy was done on the 26/8/2018. Imaging confirmed a mixed lytic/productive mass in the right frontal sinus with erosion through the calvarium. The biopsy was consistent with squamous cell carcinoma. She was then referred to the oncology service to discuss treatment options on 21/8/2018.

Given the advanced extent of the local tumour radiation therapy was discussed as the optimal treatment option to be followed by adjuvant chemotherapy. Thoracic CT scan was done on 21/8/2018 which showed no evidence of metastatic disease and as such radiation treatment planning was pursued.

A stereotactic radiation regimen of 3 X 8.75Gy fractions was initiated on 23/8/2018. This was very well tolerated and apart from alopecia and variable dermal pigmentary changes within the field, no acute adverse effects were noted. Adjuvant palladia chemotherapy was initiated on 20/9/2018 and was continued for 6 months.

Marked reduction in swelling was noted over the following weeks to months with resolution of head pain. A follow up CT scan was done on the 7/5/2019 which showed marked reduction of tumour volume as well as some remodelling of the calvarium defect. The patient presented with recurrent disease in July 2020 and received a second course of radiation therapy and passed away 2 years and 4 months after initial diagnosis.