Given an enlarged thyroid with multiple right‑sided nodules extending partially into the mediastinum, mild tracheal deviation but no airway compression or suspicious lymph nodes, which specialist should the patient be referred to?

Endocrinology Referral for Multinodular Goiter with Substernal Extension

The patient should be referred to an endocrinologist for initial evaluation, risk stratification, and fine-needle aspiration biopsy of the thyroid nodules, with subsequent surgical referral to an endocrine surgeon if malignancy is confirmed or if compressive symptoms warrant intervention. 1, 2

Primary Specialist: Endocrinology

Endocrinology should serve as the first point of contact because the core clinical question is whether these multiple thyroid nodules harbor malignancy, which requires systematic ultrasound-based risk stratification and selective fine-needle aspiration biopsy—both within the endocrinologist's scope of practice. 1, 3, 4

Rationale for Endocrinology as Initial Specialist

• Any palpable thyroid nodule >1 cm warrants endocrinology evaluation for ultrasound characterization and potential FNA, regardless of whether the gland is multinodular or solitary. 1

• Multinodular goiter requires selective biopsy of the most suspicious nodules based on ultrasound features (hypoechogenicity, microcalcifications, irregular margins, solid composition, central hypervascularity), not indiscriminate sampling of all nodules. 1, 5, 4

• The endocrinologist will measure serum TSH to determine whether the nodules are autonomously functioning (which would alter the diagnostic pathway) and assess for thyroid dysfunction. 5, 3, 6

• Serum calcitonin measurement should be considered as part of the diagnostic workup to screen for medullary thyroid carcinoma, which has higher sensitivity than FNA alone and is particularly important in multinodular disease. 1, 6

Specific Diagnostic Steps the Endocrinologist Will Perform

• High-resolution ultrasound with complete cervical lymph node evaluation to characterize nodule size, composition, echogenicity, margins, calcifications, and vascularity, plus assessment of central and lateral neck lymph node basins for suspicious features (loss of fatty hilum, microcalcifications, cystic change). 1, 2

• Ultrasound-guided FNA of the largest nodule and any nodule with ≥2 suspicious features, prioritizing nodules >1 cm with concerning sonographic characteristics over smaller or purely cystic lesions. 1, 2, 4

• Bethesda classification of cytology results to stratify malignancy risk: benign (1-3% cancer risk), indeterminate (12-34% risk depending on subcategory), suspicious (60-75% risk), or malignant (97-99% risk). 1

• Molecular testing for BRAF, RAS, RET/PTC, and PAX8/PPARγ mutations if FNA yields indeterminate cytology (Bethesda III or IV), as 97% of mutation-positive nodules are malignant. 1, 2

When to Refer to Endocrine Surgery

Surgical referral is indicated only after cytologic or molecular confirmation of malignancy, or when compressive symptoms clearly attributable to the goiter are present. 1, 2, 5

Absolute Indications for Surgical Referral

• Bethesda V (suspicious) or VI (malignant) cytology warrants immediate referral for total or near-total thyroidectomy with pre-operative lymph node compartment assessment. 1, 2

• Follicular neoplasm (Bethesda IV) with normal TSH and "cold" appearance on thyroid scan requires surgical excision for definitive diagnosis, as FNA cannot distinguish follicular adenoma from carcinoma. 1, 2

• Compressive symptoms clearly attributable to the goiter—dysphagia, dyspnea, choking sensation, or airway obstruction—that interfere with quality of life despite the absence of malignancy. 5, 3, 7

• Substernal extension causing tracheal deviation (as in this patient) may eventually require surgery if the goiter enlarges further or symptoms develop, but mild tracheal shift without airway compression does not mandate immediate surgery. 5, 4

Relative Indications for Surgical Referral

• Nodules >4 cm regardless of ultrasound appearance, due to increased false-negative rate of FNA and higher risk of compressive symptoms. 1

• Confirmed metastatic, multifocal, or familial differentiated thyroid carcinoma, regardless of nodule size. 1

• Rapidly growing nodule (≥3 mm increase in any dimension during surveillance), as rapid growth is one of the strongest predictors of malignancy. 1

Why Not Refer Directly to Surgery?

Proceeding directly to thyroidectomy without tissue diagnosis may result in inappropriate surgical extent and unnecessary removal of benign tissue, as the vast majority of multinodular goiters are benign. 1, 5, 4

• Approximately 5-15% of thyroid nodules are malignant, meaning 85-95% are benign and do not require surgery. 1, 5, 6

• Cytological confirmation before surgical planning allows the surgeon to determine the appropriate extent of resection (lobectomy vs. total thyroidectomy) and whether lymph node dissection is needed. 1

• Overdiagnosis and overtreatment of benign thyroid nodules is common, leading to unnecessary procedures, lifelong thyroid hormone replacement, and surgical complications (recurrent laryngeal nerve injury, hypoparathyroidism). 1

Management Algorithm for This Patient

Step 1: Endocrinology Consultation

• Measure serum TSH, free T4, and consider serum calcitonin. 1, 5, 3, 6

• Perform high-resolution ultrasound with complete cervical lymph node evaluation. 1, 2

• Perform ultrasound-guided FNA of the largest right-sided nodule and any nodule >1 cm with ≥2 suspicious features (hypoechogenicity, microcalcifications, irregular margins, solid composition, central hypervascularity). 1, 2

Step 2: Management Based on FNA Results

• If Bethesda II (benign): Surveillance with repeat ultrasound at 12-24 months to assess for interval growth or development of suspicious features. 1, 2

• If Bethesda III (AUS/FLUS) or IV (follicular neoplasm): Consider molecular testing (BRAF, RAS, RET/PTC, PAX8/PPARγ) to refine malignancy risk; if molecular testing is positive or unavailable, proceed to diagnostic lobectomy. 1, 2

• If Bethesda V (suspicious) or VI (malignant): Immediate referral to endocrine surgeon for total or near-total thyroidectomy with pre-operative lymph node compartment assessment. 1, 2

• If nondiagnostic/inadequate sample: Repeat FNA under ultrasound guidance; if repeat FNA remains nondiagnostic, consider core needle biopsy or surgical excision depending on clinical suspicion. 1

Step 3: Monitoring for Compressive Symptoms

• Monitor for dysphagia, dyspnea, voice changes, or worsening tracheal deviation during surveillance, as these symptoms would prompt surgical referral even if cytology is benign. 5, 3, 7

• Substernal extension with mild tracheal deviation but no airway compression does not mandate immediate surgery, but warrants close monitoring with serial imaging to assess for progressive enlargement. 5, 4

Critical Pitfalls to Avoid

• Do not refer directly to surgery without cytologic confirmation of malignancy or clear compressive symptoms, as this leads to overtreatment of benign disease. 1, 5, 4

• Do not rely on clinical examination alone to differentiate benign from malignant nodules, as palpation cannot reliably distinguish the two. 1

• Do not perform radionuclide scanning in euthyroid patients to determine malignancy risk, as ultrasound features are far more predictive and most thyroid cancers occur in patients with normal thyroid function. 1, 8

• Do not biopsy all nodules in a multinodular gland—selectively target the largest nodule and those with the most suspicious ultrasound features. 1, 2, 5

• Do not override a reassuring FNA when worrisome clinical findings persist, as false-negative results occur in up to 11-33% of cases; repeat FNA or surgical excision may be warranted if clinical suspicion remains high. 1