Primary thyroid lymphoma
Primary thyroid lymphoma is a rare non-Hodgkin lymphoma arising within the thyroid gland, most often in patients with longstanding Hashimoto thyroiditis, presenting as a rapidly or subacutely enlarging neck mass sometimes with B symptoms (fever, night sweats, weight loss). Diagnosis rests on excisional or core biopsy showing lymphoma, and treatment follows general aggressive B-cell non-Hodgkin lymphoma principles: radiation with or without chemotherapy for localized disease, and R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) for more extensive disease.
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What this article covers
- Overview
Definition: primary thyroid lymphoma is a rare non-Hodgkin lymphoma (NHL) that arises within the thyroid gland itself, rather than involving the thyroid secondarily from disseminated systemic lymphoma.
- Epidemiology
A rare cause of thyroid malignancy, distinct from and far less common than the epithelial thyroid cancers (papillary, follicular, medullary, and anaplastic carcinoma).
- Risk factors
Hashimoto thyroiditis (autoimmune hypothyroidism): the principal recognized risk factor, with antithyroglobulin and anti-thyroid peroxidase antibody-associated thyroid destruction preceding lymphoma development in many patients.
- Pathophysiology
Longstanding lymphocytic infiltration of the thyroid in Hashimoto thyroiditis provides a substrate of chronically stimulated, proliferating lymphoid tissue within the gland from which a clonal lymphoid malignancy can emerge.
- Clinical features
A neck mass, which may enlarge rapidly or subacutely, often in a patient with known or previously unrecognized Hashimoto thyroiditis.
- Differential diagnosis
Anaplastic thyroid carcinoma: also presents as a rapidly enlarging neck mass, but is an epithelial malignancy rather than lymphoid, distinguished on biopsy by undifferentiated carcinoma cells rather than lymphoma histology.
- Diagnosis
The clinching diagnostic basis is tissue biopsy demonstrating lymphoma, obtained by excisional or core-needle biopsy rather than FNA alone, since FNA cytology alone is not considered sufficient to…
- Management
First, confirm the diagnosis and stage with excisional/core biopsy, cross-sectional imaging, and bone marrow biopsy before initiating treatment.
- Complications
Airway or esophageal compression from thyroid enlargement before treatment response.
- Prognosis
Localized disease treated with radiation and chemotherapy generally has a favorable outcome, consistent with the general principle that localized (stage I/II) aggressive lymphoma without B symptoms responds well to combined-modality therapy.
- Prevention
There is no established means of preventing primary thyroid lymphoma.
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Related articles
- Hashimoto thyroiditis
Hashimoto thyroiditis is a chronic autoimmune process in which lymphocytic infiltration destroys the thyroid, and is the most common cause of hypothyroidism in iodine-sufficient regions such as the United States. Diagnosis rests on an elevated thyroid-stimulating hormone with a low or normal free thyroxine, and first-line treatment is lifelong levothyroxine replacement dosed to normalize thyroid-stimulating hormone.
- 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.
- 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.
- Hypothyroidism
Hypothyroidism is thyroid hormone deficiency, most commonly caused by autoimmune (Hashimoto) thyroid failure in iodine-sufficient countries, diagnosed by an elevated thyroid-stimulating hormone with a low or normal free thyroxine. First-line treatment is levothyroxine dosed at 1.6 mcg/kg lean body weight orally once daily, titrated using thyroid-stimulating hormone rechecked no sooner than 6 weeks after any dose change.