A 58-year-old woman with a long-standing goitre presents with weight loss, tremor and atrial fibrillation. Free T4 is elevated and TSH is suppressed. A technetium-99m thyroid scan shows multiple discrete areas of increased uptake with suppressed uptake in the intervening tissue. What is the most likely diagnosis?
- A Graves disease
- B Subacute (de Quervain) thyroiditis
- C Toxic multinodular goitre (Plummer disease) ✓
- D Solitary toxic adenoma
Correct answer: C. Toxic multinodular goitre (Plummer disease)
Explanation
Toxic multinodular goitre shows a heterogeneous scan with multiple autonomously functioning hot nodules and suppressed uptake between them, reflecting somatic activating mutations arising independently in several nodules. Graves disease shows diffuse homogeneous uptake throughout an enlarged gland. Solitary toxic adenoma shows a single hot focus with complete suppression of the rest of the gland. De Quervain thyroiditis shows globally reduced uptake because inflamed follicles cannot trap tracer.
Reference: Williams Textbook of Endocrinology, 13th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.