Oncocytic thyroid carcinoma
Oncocytic thyroid carcinoma is a rare thyroid malignancy arising from follicular-derived thyroid epithelium, presenting as a thyroid nodule that, like follicular neoplasms generally, cannot be distinguished from its benign counterpart by cytology alone; the diagnosis of malignancy requires surgical histology showing capsular or vascular invasion. Management follows the same framework used for other follicular-derived thyroid carcinomas: thyroidectomy, followed by TSH-suppressive levothyroxine and, for intermediate- to high-risk disease, radioactive iodine and thyroglobulin-based surveillance.
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What this article covers
- Overview
Definition: oncocytic thyroid carcinoma is a rare thyroid malignancy of follicular-derived origin, evaluated and managed within the same general framework used for other thyroid nodules and follicular-derived thyroid carcinomas.
- Epidemiology
A rare thyroid malignancy relative to papillary carcinoma (80-90% of thyroid cancer) and follicular carcinoma (10-15%), which together account for the great majority of thyroid cancer diagnoses.
- Risk factors
A history of ionizing radiation exposure, particularly in childhood (for example, prior treatment of childhood cancer or exposure from a nuclear accident), is a recognized risk factor for thyroid cancer generally.
- Pathophysiology
Oncocytic thyroid carcinoma arises from follicular-derived thyroid epithelium, placing it in the same broad lineage as papillary and follicular carcinoma rather than the parafollicular C-cell origin of medullary carcinoma.
- Clinical features
Presents as a thyroid nodule, identified by palpation, on routine examination, or incidentally on imaging performed for another reason, following the general presentation of thyroid neoplasms.
- Differential diagnosis
Benign oncocytic (Hurthle cell) adenoma: shares the same cytologic appearance on FNA and is distinguished only by the absence of capsular or vascular invasion on surgical histology, unlike the invasive histology of carcinoma.
- Diagnosis
The clinching diagnostic basis is histologic demonstration of capsular or vascular invasion on the surgically excised specimen, since FNA cytology of a follicular-pattern (oncocytic) nodule cannot by…
- Management
First, surgical excision (thyroid lobectomy or total thyroidectomy) both establishes the diagnosis and provides initial treatment, with the extent of surgery guided by nodule size (unilateral…
- Complications
Postoperative hypocalcemia from parathyroid injury or removal during thyroidectomy.
- Prognosis
Overall 5-year survival for thyroid cancer is 98.1%, reflecting the generally favorable outlook for differentiated thyroid cancer as a category, though this figure is not specific to oncocytic histology.
- Prevention
There is no established primary prevention for oncocytic thyroid carcinoma.
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Related articles
- 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.
- 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.
- 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.