Abstract
Papillary thyroid carcinoma is a common malignancy to affect the thyroid and is typified by a nonaggressive nature and low rates of mortality. In contrast, anaplastic thyroid carcinoma is the most aggressive thyroid malignancy with a mortality rate of nearly 90% and survival typically of only six months after the diagnosis is made. The transformation of papillary thyroid carcinoma to anaplastic thyroid carcinoma is well documented in the literature but is uncommon and in most instances is reported as a case report or small series only. Transformation of papillary thyroid carcinoma to anaplastic thyroid carcinoma usually takes place in the thyroid itself or in the adjacent lymph nodes. Only on rare occasions does a transformation occur in a papillary thyroid carcinoma metastasis outside of these locations. In the present case report and subsequent discussion we highlight an unusual case of PTC with transformation to anaplastic thyroid carcinoma, which is shown to involve numerous locations to include near total lung parenchyma obliteration. We also discuss the differential diagnostic challenges when faced with a thyroid malignancy that is negative for thyroglobulin.
Highlights
Papillary thyroid carcinomas are typically nonaggressive tumors with the survival for stage I disease approximating 100% [1]
Case Reports in Pathology (a) case report we describe a papillary thyroid carcinoma, which takes on an aggressive form by transforming into a multifocal anaplastic thyroid carcinoma
The immunostains TTF-1, thyroglobulin, PAX8, and Napsin-A are markers that are used in the differential diagnosis of papillary thyroid carcinoma (PTC) from primary lung adenocarcinoma
Summary
Papillary thyroid carcinomas are typically nonaggressive tumors with the survival for stage I disease approximating 100% [1]. Certain hereditary conditions are well known to be associated with an increased risk for the development of thyroid cancer and include multiple endocrine neoplasia 2a, multiple endocrine neoplasia 2b, familial adenomatous polyposis, Cowden disease, Carney complex, type I, and familial nonmedullary thyroid carcinoma [1]. Radiation exposure is another well-known risk factor for the development of thyroid carcinoma [1]. Case report we describe a papillary thyroid carcinoma, which takes on an aggressive form by transforming into a multifocal anaplastic thyroid carcinoma. The burden of disease, distant metastases, and multifocality of transformation in this particular case was incredible and afforded us the opportunity to present an interesting case of transformation
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