Primary retropharyngeal leiomyosarcoma in a young cat.

Case summary: An Oriental Shorthair cat, aged 1 year and 6 months, developed progressive stridor and a palpable right ventral cervical mass. Fine-needle aspiration of the mass was inconclusive, while thoracic radiography and CT showed no evidence of metastasis. There was initial improvement in stridor with oral doxycycline and prednisolone treatment, but it recurred 4 weeks later and excisional biopsy was performed. Histopathology with immunohistochemistry diagnosed leiomyosarcoma with incomplete surgical margins. Adjunctive radiation therapy was declined. Repeated physical examination and CT 7 months postoperatively documented no evidence of mass recurrence.

Relevance and novel information: This is the first reported case of retropharyngeal leiomyosarcoma in a young cat with no evidence of local reoccurrence 7 months following an excisional biopsy.