Warthin’s Tumor

Clinical Features

- M>F, 5th to 7th decade
- Strong association with smoking
- Almost exclusively parotid (superficial lobe, inferior pole)
- 10% multifocal, 10% bilateral

Cytologic features on FNA

- Sparsely cellular
- Sheets of oncocytes – orderly arrangement, no 3D crowding, no glandular formation or microacini
- Uniform, round, eccentric nuclei with even chromatin, indistinct nucleoli, granular cytoplasm
- May see mild atypia, prominent nucleoli – not sign of malignancy
- Degenerated oncocytes may be pyknotic with dense orangeophilic cytoplasm
- Mixed population of lymphocytes
- Granular background, may see atypical squamous metaplasia

Gross features

Round to oval, encapsulated mass 2-5 cm with a smooth or lobulated surface
Cut surface is pale gray
Cystic spaces (mucoid or brown exudates) with papillary projections from cysts
Solid white areas represent lymphoid follicles

Microscopic

Cystic spaces are lined by a double layer of cells, resting on a dense lymphoid stroma
The surface layer is oncocytic; the basal layer is cuboidal to polygonal
May see foci of squamous metaplasia

Prognosis

Benign; recurrence rate of 2% after resection
Transformation to malignancy is very rare and may include epithelial or lymphoid component
a.    Most common malignancies arising from Warthin’s are squamous cell carcinoma, lymphoma, mucoepidermoid carcinoma