Thyroglobulin is a glycoprotein expressed by thyroid follicular cells. It is a specific marker for thyroid derivation, and may be useful in the work-up of carcinomas of unknown primary. It may be less sensitive in less differentiated thyroid tumors, as anapestic thyroid carcinoma is notorious for not staining with about anything.
Pitfalls
- Medullary thyroid carcinoma does not express thyroglobulin.
- Thyroglobulin can have a lot of artifactual staining, which may cause difficultly diagnosing tumors like medullary carcinoma (expected to be thyroglobulin negative).
- Dedifferentiated thyroid tumors may not express thyroglobulin.
Photomicrographs
References:
Fischer, S., & Asa, S. L. (2008). Application of immunohistochemistry to thyroid neoplasms. Archives of Pathology & Laboratory Medicine, 132(3), 359–372.