OVERVIEW
• Warthin’s tumor or papillary cystadenoma lymphomatosum is the second most common benign salivary gland tumor, that occurs almost always in the parotid gland. It accounts for about 15% of all epithelial tumors of the parotid gland.
• The disease was named after the pathologist who described and published the two case reports in the American literature in 1929.
• The parotid gland is situated in front of and below the ear. The normal gland consists of glandular cells that make enzyme that help to breakdown the food we eat. These enzymes are carried to the mouth by tiny ducts lined epithelial cells
• In Warthin’s tumor, the normal function of the parotid gland is affected as the parotid ducts stop functioning properly

ETIOLOGY AND RISK FACTORS
• The etiology of Warthin’s tumor is not known but the most common risk factor is chronic smoking of more than 20 years.
• Other non-modifiable risk factors include elderly age group, male gender and being Caucasian

PATHOGENESIS OF WARTHIN’S TUMOR
• It is believed that this tumor develops in heterotopic (location of a tissue outside its normal position) parotid gland tissue within peri- and intra parotid lymph nodes.
• During fetal development of the parotid gland, the epithelial cells migrate into the surrounding lymphocyte-rich tissue.
• The late encapsulation of the parotid gland explains the occurrence of intra parotid lymph nodes and heterotopic salivary gland remnants entrapped in the parotid lymph nodes.

CLINICAL FEATURES OF WARTHIN TUMOR
• Since it is a slow growing tumor it may be initially asymptomatic
• With increase in size it presents as a painless lump in front of the ear
• Symptoms occur mainly due to pressure effects on the adjacent structures eg the facial nerve causing impaired hearing, earache, tinnitus and rarely facial paralysis
• At diagnosis, the tumor usually measures 2 cm to 4 cm but may occasionally be much larger. Average duration is almost two years before diagnosis.

MACROSCOPIC (GROSS) APPEARANCE
• Warthin’s tumor is spherical to oval in shape and almost always well circumscribed by a connective tissue capsule.
• The cut surface shows cysts of varying numbers and size that exude clear, or brown fluid or semisolid necrotic debris.
• Slit like spaces lumens containing small knoblike excrescences may be visible on the cut surface.
• The space between the cysts may show foci of hemorrhage.

MICROSCOPIC APPEARANCE
• These tumors are well encapsulated and demarcated from the adjacent normal tissue.
• The term papillary cystadenoma lymphomatosum describes the microscopic appearance rather well.
• It consists of a mixture of solid areas and cystic spaces.
• The cystic spaces are lined by two layered epithelium, thrown into papillary folds, and the cystic spaces contain serous fluid and cellular debris.
• The epithelial cells show infiltration with lymphocytes often with germinal center formation similar to that seen in the histology of a lymph node.

DIAGNOSIS OF WARTHIN TUMOR
• Presence of painless mass in front of the ear that may be fluctuant
• The site of swelling and extent is confirmed by imaging with an x-ray, ultrasound CT scan or MRI
• Finally a tissue biopsy is often done to confirm the histological diagnosis which shows the microscopic appearances described above

TREATMENT OF WARTHIN TUMOR
Surgical removal of the mass is the preferred treatment of choice, removing as much of the tumor as possible without damaging the nerves passing through the parotid gland

WARTHIN’S TUMOR – KEY POINTS
• Warthin’s tumor is a benign tumor of the parotid gland
• It is also referred to as papillary cystadenoma lymphomatosum
• Presents as a painless slow growing lump
• Can cause impaired hearing, ear pain and tinnitus
• Diagnosed by CT scan or MRI and tissue biopsy
• Histology shows cystic spaces lined by epithelial cells thrown into folds and infiltrated by lymphocytes forming germinal centers
• Treatment is by surgical excision