Two concurrent embryonal rhabdomyosarcomas of the oesophageal and perilaryngeal tissue in an adult dog: imaging, cytological and histological features

A five-year-old neutered male Labrador Retriever was presented for recurring severe dyspnoeic episodes. Oral examination performed under sedation revealed a mass originating from the left arytenoid. CT highlighted a large perilaryngeal soft-tissue mass abutting the oesophagus, with a small intralaryngeal component. The mass created a narrowing of the laryngeal lumen and displaced the cranial cervical oesophagus dorsally and to the right. CT also highlighted a second smaller mass rostrally at the level of an oesophageal outpouching, narrowing the caudal aspect of the nasopharynx. The perilaryngeal mass was aspirated under ultrasound guidance. Cytology was suggestive of a tumour arising from skeletal muscle and a rhabdomyosarcoma was suspected. Due to poor prognosis, the patient was euthanased. Postmortem examination confirmed two masses affecting the cranial cervical oesophagus, one of which also invaded the perilaryngeal tissue. Histology and immunohistochemistry provided a final diagnosis of two concurrent oesophageal and perilaryngeal embryonal rhabdomyosarcomas.