Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 78-year-old woman is evaluated for a rapidly enlarging neck mass that has been present for 4 weeks and is associated with neck discomfort, dysphagia, and hoarseness. The patient has had Hashimoto thyroiditis and hypothyroidism since age 24 years and has been taking levothyroxine since that time.

Physical examination reveals an older woman in severe distress. Temperature is 39.4 °C (102.9 °F), blood pressure is 145/75 mm Hg, pulse rate is 110/min, and respiration rate is 16/min; BMI is 23. Pulmonary examination reveals dyspnea with bilateral basilar rhonchi, and cardiac examination shows tachycardia without a murmur. The thyroid gland is enlarged and firm without nodules. Facial plethora and distended bilateral cervical neck veins are noted. The patient is hoarse. Bilateral cervical lymphadenopathy is palpated. Although neurologically intact, she finds it difficult to concentrate when asked questions.

A thyroid ultrasound shows an enlarged thyroid gland with heterogeneous echotexture but no specific nodularity and multiple bilateral cervical lymph nodes measuring 1 to 3 cm in diameter.

Which of the following is the most likely diagnosis?

A: Bleeding into the thyroid gland
B: Medullary thyroid cancer
C: Papillary thyroid cancer
D: Primary thyroid lymphoma

MKSAP Answer and Critique

The correct answer is D: Primary thyroid lymphoma.

This patient most likely has primary thyroid lymphoma. A benign goiter would not grow this rapidly and is unlikely to be associated with local symptoms. Thyroid lymphoma occurs most frequently in older patients who have a history of Hashimoto thyroiditis. Primary thyroid lymphoma typically presents as an enlarging neck mass, often with evidence of local compression of adjacent structures (such as dysphagia, hoarseness, stridor, jugular vein distention, and facial edema) and systemic symptoms (“B” symptoms) of lymphoma (such as fever, weight loss, and night sweats). A thyroid fine-needle aspiration (FNA) biopsy can suggest the diagnosis, but a core-needle or excisional biopsy is often needed to establish the diagnosis of lymphoma. Most primary thyroid lymphomas are mucosa-associated lymphoid tumors and respond to systemic chemotherapy. This patient’s distended bilateral cervical neck veins suggest obstruction at the level of the thoracic inlet (that is, the thyroid gland).

Bleeding into the thyroid gland is unlikely because the gland is firm on physical examination, without any evidence of fluctuance, and the thyroid ultrasound shows heterogeneous echotexture rather than a cystic mass. Additionally, the patient has Hashimoto thyroiditis (which can predispose to lymphoma), has no history of neck trauma, and was not taking an anticoagulant medication.

With medullary and papillary thyroid cancers, the thyroid gland most likely would contain specific thyroid nodules. These cancers generally grow relatively slowly.

Key Point

• Thyroid lymphoma occurs most frequently in older patients with a history of Hashimoto thyroiditis and typically presents as an enlarging neck mass, often with local and systemic symptoms.

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