Cystadenoma Lymphomatosum-like Lesion in the Parotid Salivary Gland of a Mouse

Papillary cystadenoma lymphomatosum or adenolymphoma, commonly referred to as Warthin's tumor, is a lesion of the parotid salivary gland in humans generally considered to be a benign t ~ m o r . ~ . ' ~ Although only one of the parotid glands is usually affected, bilateral involvement4 and extraparotid location^^.^ have been reported. Papillary cystadenoma lymphomatosum characteristically consists of multiple papillary cysts lined by a double-layer epithelium and a dense lymphoid stroma. The histogenesis of Warthin's tumor has not been clearly elucidated; a dysgenesis,,J2 n e o p l a ~ m , ~ ~ ~ and inflammatory have all been proposed. Salivary gland lesions morphologically similar to cystadenoma lymphomatosum described in humans have not been reported in animals. One of the parotid salivary glands in a 2-year-old female B,C3F, hybrid mouse used as a control in a bioassay study had a slightly enlarged parotid salivary gland. The enlarged gland, the unaffected contralateral salivary gland, and both sublingual and submaxillary salivary glands were fixed in 10% buffered formalin, embedded in paraffin, cut at 6 pm and stained with hematoxilyn and eosin (HE) and periodic acid-Schiff (PAS). Microscopically, the affected salivary gland was replaced by multiple cystic tubular structures and lymphoid tissue