Sadie, a three year old, spayed female Shetland Sheepdog presented for a mass on the dorsal aspect of the head that had been first noticed approximately one month prior to presentation. She had been treated with a course of amoxicillin/clavulanic acid and the mass did not respond, so the primary veterinarian performed a fine needle aspirate. This was consistent with squamous cell hyperplasia and dysplasia, but squamous cell carcinoma could not be ruled out. Three-view thoracic radiographs were also taken at this time along with mandibular lymph node aspirates, which did not show any evidence of metastatic disease, and blood tests (CBC/chemistry panel) were unremarkable
Based on this presentation a CT scan and incisional biopsy were performed.
CT scan revealed a large, partially contrast enhancing mass involving the frontal sinuses. As you can see from the attached image, the majority of the disease is located in the sinuses and surrounding area, with little to no mass in the rest of the nasal cavity.
Biopsy was consistent with a squamous cell carcinoma.
Squamous cell carcinoma of the frontal sinus is a rare disease in dogs. In the few reported cases, average age tends to be younger than dogs with other tumors. In humans and in dogs these tumors are usually diagnosed at an advanced stage, meaning that there is disease extending beyond the sinus cavity.
In one report of three dogs treated with piroxicam and carboplatin all three had a significant clinical response (de Vos et al, Vet Comp Oncol 2012). In our experience, these tumors can be very responsive to treatment. In some cases, treatment with a non-steroidal anti-inflammatory alone may result in a complete remission. However, given the aggressive nature of these tumors recurrence is common.
Long term tumor control may be possible with more aggressive treatments. In this case the owners opted for palliative radiation therapy combined with a non-steroidal anti-inflammatory, firocoxib (Previcox®). The mass on the dorsal aspect of the head resolved during the course of radiation and continued to shrink after treatment, until it completely resolved. This image shows our patient after radiation, notice complete resolution of the mass on the dorsal head.
Following radiation therapy, the patient continued receiving piroxicam and started on Toceranib (Palladia TM).
Fourteen months after completing radiation a mass recurred in the area and cytology confirmed squamous cell carcinoma. Our patient still has a reasonably good quality of life, on pain medications and antiinflamatories.