Subacute thyroiditis (de Quervain) presenting as a painless "cold" nodule.

Area of Science:

• Endocrinology
• Nuclear Medicine
• Pathology

Background:

• Thyroid nodules are common, with a significant proportion requiring further investigation.
• Differentiating benign from malignant thyroid lesions is critical for appropriate patient management.
• Subacute thyroiditis is an inflammatory condition of the thyroid gland, often self-limiting.

Observation:

• A 49-year-old woman presented with a solitary, painless, non-tender nodule in the left thyroid lobe.
• Thyroid scintigraphy showed a "cold" area and decreased radioactive iodine uptake (9%).
• Needle aspiration cytology unexpectedly revealed subacute thyroiditis despite the absence of typical clinical symptoms.

Findings:

• The initial presentation of subacute thyroiditis mimicked a solitary thyroid nodule.
• Within a month, the patient developed widespread thyroid involvement, evidenced by suppressed radioiodine uptake and elevated thyroid hormones.
• Cytology is essential for diagnosing subacute thyroiditis in atypical presentations.

Implications:

• Subacute thyroiditis should be included in the differential diagnosis for solitary, painless, "cold" thyroid nodules.
• This case highlights the importance of considering inflammatory conditions in thyroid nodule evaluation.
• Accurate early diagnosis of subacute thyroiditis can prevent unnecessary invasive procedures for presumed nodules.