Anaplastic thyroid carcinoma
Anaplastic thyroid carcinoma is a rare, highly aggressive, undifferentiated thyroid malignancy that presents as a rapidly enlarging neck mass, arising de novo or from a preexisting differentiated thyroid cancer, and is often unresectable at diagnosis with a median survival of about 5 months. Treatment is largely palliative multimodality therapy with surgery when feasible, external beam radiation therapy, and chemotherapy, since the disease has typically outpaced the possibility of cure by the time it is recognized.
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What this article covers
- Overview
Definition: anaplastic thyroid carcinoma is a rare, highly aggressive, undifferentiated malignancy of the thyroid gland, arising either de novo or in a patient with a preexisting differentiated (papillary or follicular) thyroid cancer.
- Epidemiology
A rare thyroid malignancy, occurring far less often than the differentiated thyroid cancers (papillary carcinoma, 80-90% of thyroid cancer; follicular carcinoma, 10-15%), leaving anaplastic and…
- Risk factors
A preexisting differentiated thyroid cancer (papillary or follicular carcinoma) is a recognized substrate from which anaplastic carcinoma can arise through dedifferentiation.
- Pathophysiology
Anaplastic thyroid carcinoma represents dedifferentiation of thyroid follicular epithelium, losing the architectural and functional features (including iodine uptake) that characterize papillary and follicular carcinoma.
- Clinical features
A rapidly enlarging neck mass that is often painful and progresses over weeks, unlike the typically painless, slow-growing nodule of differentiated thyroid cancer.
- Differential diagnosis
Papillary or follicular thyroid carcinoma: both grow far more slowly and are usually painless, unlike the rapid, often painful enlargement of anaplastic carcinoma; they also remain iodine-avid, unlike anaplastic carcinoma.
- Diagnosis
The clinching diagnostic basis is tissue confirmation, by fine-needle aspiration (FNA) or core/open biopsy, of undifferentiated malignant epithelial cells arising in the thyroid, in a patient…
- Management
First, assess resectability; if the tumor is resectable, surgical excision is undertaken as part of a combined surgery-radiation-chemotherapy plan.
- Complications
Airway obstruction from local tracheal invasion or compression, potentially requiring emergency airway intervention.
- Prognosis
Poor, with a median survival of about 5 months from diagnosis, among the worst of any solid tumor.
- Prevention
There is no established primary prevention for anaplastic thyroid carcinoma.
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Related articles
- Papillary thyroid carcinoma
Papillary thyroid carcinoma is the most common thyroid malignancy, arising from thyroid follicular cells and typically spreading to cervical lymph nodes with a low risk of distant metastasis. Diagnosis rests on ultrasound risk stratification and fine-needle aspiration biopsy, and treatment is thyroid lobectomy or total thyroidectomy, with postoperative radioactive iodine and thyroid-stimulating-hormone-suppressive levothyroxine reserved for intermediate to high risk disease.
- Follicular thyroid carcinoma
Follicular thyroid carcinoma is the second most common differentiated thyroid cancer, accounting for 10% to 15% of thyroid cancer cases, and characteristically spreads hematogenously to lung, bone, and brain rather than to cervical lymph nodes. Because fine-needle aspiration cytology cannot reliably distinguish it from a benign follicular adenoma, diagnosis often requires diagnostic lobectomy, and treatment is surgery followed by postoperative radioactive iodine and thyroid-stimulating-hormone-suppressive levothyroxine for higher-risk disease.
- Medullary thyroid carcinoma
Medullary thyroid carcinoma is a neuroendocrine tumor of the parafollicular C cells that secretes calcitonin and is familial (RET-mutant, part of MEN2A or MEN2B) in about 25% of cases. First-line treatment is total thyroidectomy with central neck lymph node dissection, with any coexisting pheochromocytoma resected first, followed by lifelong levothyroxine replacement and calcitonin/CEA surveillance; selpercatinib, a RET kinase inhibitor, is used for unresectable or metastatic RET-mutant disease.
- Thyroid nodules
A thyroid nodule is a discrete structural lesion within an otherwise normal thyroid gland, found on ultrasound in about 40% of the United States population though palpable in far fewer, and malignant in roughly 5%. Evaluation begins with a thyroid-stimulating hormone (TSH) level and thyroid ultrasonography, and management is surveillance for benign or low-risk nodules, with lobectomy or total thyroidectomy reserved for cytology suspicious for or diagnostic of malignancy.