Squamous Cell Carcinoma

Epidemiology

Primary squamous cell carcinoma (SCCA) of the parotid gland is a rare tumor and accounts for 1% of parotid tumors. SCCA comprises 3% of submandibular gland neoplasms and 4% of submandibular carcinomas. These tumors are more common in men.

Primary parotid SCCA should be considered a diagnosis of exclusion and should be made only after excluding the other neoplasms that could mimic its appearance. SCCA of the parotid gland can be confused with high-grade mucoepidermoid carcinoma or may occur from direct spread of SCCA arising from the external ear. In our experience, SCCA identified in the parotid gland is due to lymphatic drainage to intraparotid lymph nodes from skin cancer. The most common primary site locations for the cutaneous lesions include the temporal region, lateral face, eyelid, and scalp. These areas must be thoroughly examined in patients who are diagnosed with primary parotid SCCA.

Clinical Findings

These tumors usually present in the sixth or seventh decade as a rapidly enlarging mass. On clinical examination, these lesions are usually fixed to adjacent structures and often invade the overlying skin. Approximately 20% of patients complain of pain, with about 10% of patients having facial nerve palsy.

Pathology

The etiology of these tumors is unknown. Squamous epithelium is not normally found within the salivary gland. It is possible that squamous metaplasia may arise secondary to chronic inflammation. The site of origin is thought to be the salivary ducts. However, these tumors are often very advanced at presentation, making it difficult to identify a site of origin.