A tonsillar squamous cell carcinoma in a 6-year-old male Cocker Spaniel
The following are histopathology (H&E) sections from a tonsillar mass and an enlarged ipsilateral retropharyngeal lymph node.
Final Diagnosis
Tonsillar squamous cell carcinoma with metastasis to the retropharyngeal lymph node
Discussion
Squamous cell carcinomas affecting the tonsil typically arise from the tonsillar fossa epithelium. The majority of tonsillar squamous cell carcinomas metastasise early with spread to the regional lymph nodes and distant sites including lungs, liver, kidneys, spleen and bone. The retropharyngeal lymph nodes are typically first affected, followed by parotid, submandibular and prescapular lymph nodes in the later stages. Because of their large size, metastatic lesions are often mistaken for the primary tumour and therefore it is important to check the oral cavity (paying particular attention to the tonsils) when a squamous cell carcinoma is diagnosed in the neck region of a dog for example.