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thyroid oncocytic adenoma

Wednesday 15 June 2011

Digital case

- JRC:1175 : Thyroid oncocytic adenoma (Hurthle cell adenoma).
- JRC:2669 : Anaplastic (squamous cell) carcinoma, arising from a preexisting Hurthle cell neoplasm.
- JRC:14913 : Thyroid oncocytic adenoma (Hurthle cell adenoma).

Definition: The thyroid oncocytic adenoma is a solitary, well-delineated and encapsulated tumor. It is characterized by a distinct mahogany brown appearance, often with central areas of scarring.

They are particularly prone to developing infarction after FNAB but Ibis phenomenon may also occur spontaneously. The tumours are composed of tells with abundant granular eosinophilic cytoplasrn and large open nuclei with prominent nucleoli, although rarely the nuclei can be hyperchromatic.

Microscopy

Like other follicular adenomas of thyroid, oncocytic follicular adenomas have a variety of architectural patterns ranging from well-formed follicles to solid and/or trabecular growth.

Colloid often appears dense and may form structures mimicking psamomma bodies.

Focally, one can see the formation of papillary structures. Occasionally, there is an almost exclusive papillary architecture. Oncocytic papillary carcinoma must be excluded and this distinction relies on establishing lack of nuclear criteria for the diagnosis of papillary carcinoma.

The distinction from oncocytic follicular carcinoma is based on the lack of capsular or vascular invasion.

Adenomatoid oncocytic nodules often occur in association with Hashimoto thyroiditis and are difficult to distinguish from truc adenomas.

Multiple oncocytic adenomas can occur, particularly in young female patients and are associated with a risk of progression to carcinoma.

The overall cytological features of oncocytic adenomas are generally similar to follicular adenomas of usual type.

The individual cells, however, are large with abundant granular eosiniphilic cytoplasm and large nuclei with promine nucleoli. They may show prominenl anisokaryosis.

See also

- thyroid adenoma
- thyroid oncocytic tumors

- oncocytic tumors (oncocytomas)

References

- Bonora E, Evangelisti C, Bonichon F, Tallini G, Romeo G. Novel germline variants identified in the inner mitochondrial membrane transporter TIMM44 and their role in predisposition to oncocytic thyroid carcinomas.Br J Cancer. 2006 Dec 4;95(11):1529-36. PMID: 17088905