[Warthin tumor of the palate: an unusual location]

Warthin's tumor (papillary cystadenoma lymphomatosum) primarily involves the parotid gland, whereas localization in the palate has been reported by a few authors. A new case of true Warthin's tumor arising from the hard palate is here presented and histogenesis and differential diagnosis are briefly discussed.

A 50 year-old woman who was referred to us because of the presence of multiple contiguous bluish cyst-like lesions involving both sides of the hard palate mucosa. The lesion was removed with a wide excision involving almost all the soft tissues of the hard palate. Histologic diagnosis (E.E stain) was: papillary cystadenoma lymphomatosum.

The histogenesis of Warthin's tumor is still controversial. The most widely accepted theory is that the tumor represents a neoplastic proliferation of salivary gland ducts entrapped in pre-existing lymph nodes. In fact, immunohistochemical analysis and cell-surface markers studies have shown that the lymphoid component is predominantly formed by T-lymphocytes, with a relatively small number of polyclonal B-lymphocytes. On the contrary, other authors found opposite relationship between T and B lymphocytes. These findings supported the concept that lymphoid tissue in Warthin's tumor represented a reactive cellular infiltrate in a pattern similar to that seen in reactive lymph nodes. Similar results have been found in this report; moreover, the hard palate does not usually contain lymphatic tissue. This could support the idea that the lymphoid tissue associated with this case is reactive and a direct origin from the ductal epithelium with secondary lymphocytic infiltration is more likely to occur in this area.