Bilateral multifocal Warthin's tumors in upper neck lymph nodes. report of a case and brief review of the literature

Cystadenolymphoma is the second most frequent benign tumor of the parotid gland representing 6 to 10% of all tumors of the salivary glands [1]. In general, Warthin's tumors present as encapsulated lesions with cystic and solid areas which usually occur in the caudal pole of the parotid gland. Initially, tumors present as an asymptomatic, slowly growing masses, affecting predominantly men (10:1) in the 5th and 6th decade [2,3]. Bilateral lesions occur in 7-10% of cases while multifocal lesions and recurrence occur in 2% of cases [4,5]. Histopathologically, they consist of a double-layer of oncocytic epithelial cells capable of forming cysts and papillary projections and a variable lymphatic stroma component [3]. Malignant transformation is very rare and the incidence of a carcinoma arising in a Warthin's tumor is approximately 1% [4]. Although pathogenesis is still unknown there is an association with cigarette smoking [3,6]. Since Honda et al. showed that the epithelial tumor components are polyclonal cell populations [7] these lesions cannot be classified as a true neoplasia anymore. This is supported by the fact that the tumors show a clinical behaviour that is typical for benign lesions and that there are only low rates for recurrence and malignant transformation [4,5,8]. Therefore, these lesions were classified as tumor-like-lesions [2,9].There are several theories to explain the origin and the development of the tumors. Only two of the theories remain, namely the hypothesis that the tumor is an adenoma with concomitant lymphocytic infiltration [2], and second the hypothesis of heterotopia of salivary tissue into peri- and intraparotideal lymph nodes [10]. The latter theory is supported by the fact that during embryogenesis of the glandula parotis a penetration of epithelial cells of the oral mucosa into lymphocyte-rich tissue takes place. Due to the late encapsulation of the parotis the occurrence of intraparotideal lymph nodes and heterotopia of salivary tissu