Warthin’s Tumor

Epidemiology

Warthin’s tumor (papillary cystadenoma lymphomatosum, cystadenolymphoma, lymphomatous adenoma) is the second most common parotid neoplasm. These tumors account for 10% of all benign parotid tumors. There is a strong male predominance, with the male to female ratio ranging from 5 to 7:1. The peak incidence appears to be between the fifth and sixth decades of life.

Clinical Findings

These lesions are usually asymptomatic. They may occasionally present as a painless mass in the parotid region. The facial nerve is almost always uninvolved.

Embryology

Warthin’s tumors are interesting lesions whose pathophysiology is directly linked to embryology. The most commonly accepted theory regarding the origin of Warthin’s tumors is that they arise from heterotopic salivary gland tissue situated within intraparotid lymph nodes. The parotid gland is the first salivary gland to develop, and initially appears between the fourth and sixth gestational weeks. The gland develops as a loose mesenchyma that contains aggregates of lymphoid tissue. The developing gland, like the other salivary glands, becomes encapsulated. However, the parotid gland is the last salivary to become encapsulated. The encapsulation of the parotid gland occurs after the development of the lymphatic system. As a result, the developing lymphoid aggregates form lymph nodes within the parotid gland. In contrast, the submandibular glands become encapsulated before the development of the lymphatic system and do not contain intraglandular lymph nodes. The intraparotid lymph nodes contain salivary ducts and acini. Warthin’s tumors arise from these ductal elements, which are located within intraparotid lymph nodes. This explains the propensity for Warthin’s tumors to be multicentric and bilateral (2–6%).