Benign, slow-growing tumor of the parotid gland.

Risk factors: Smoking, age, Caucasian, male, radiation.- Bilateral in 10%; multifocal in 10%.

Cystadenoma: Ducts grow in size and fill with serous fluid & cellular debris which forms a large cyst.Papillary: The layer of epithelial cells starts to fold into the duct, which forms a finger-like projection.Lymphomatosum: Epithelial layer gets infiltrated by lymphocytes, which organize themself to what looks like germinal centers.

Histology:- Papilli- Lymphocytes- Cystic space where the serous fluid and cellular debris are.- Not malignant → Does not break through basement membrane- Connective tissue capsule

Symptoms: - Gradual and painless unilateral swelling of the parotid- May push against nerve → impaired hearing, ear aches, tinnitus, facial paralysis

Diagnosis: - Imaging: X-ray, US, CT, MRI- Tissue biopsy

Treatment: Surgical removal with preservation of facial nerve.