Carcinoma in papillary cystadenoma lymphomatosum (Warthin's tumor).

Compared to the number of reported cases of a papillary cystadenoma lymphomatosum, malignant transformation is a rare event. This paper presents the third documented case of squamous cell carcinoma arising in the papillary cystadenoma lymphomatosum in a lymph node of the parotid region. Review of the American literature reveals 5 other cases of malignant transformation of papillary cystadenoma lymphomatosum including two cases of adenocarcinoma and one case of mucoepidermoid carcinoma with an apparent low potential for metastatic spread.