What are the next steps for a patient with a complex mass in the left thyroid lobe, a cyst and solid nodule in the right lobe, and bilateral reactive lymph nodes?

Management of Thyroid Nodules with Complex Mass in Left Lobe

Fine needle aspiration biopsy (FNA) should be performed on the complex mass in the left lobe (TR 3) as the next step in management. 1

Ultrasound Findings and Risk Assessment

• The ultrasound shows a normal-sized thyroid with symmetric lobes but heterogeneous echotexture throughout 1
• The left lobe contains a complex mass with solid isoechoic predominant component in the upper pole, with internal vascularity, measuring 2.20 x 1.47 x 0.82 cm, classified as TR 3 (mildly suspicious) 2, 1
• The right lobe contains a cyst (0.35 x 0.28 cm) and a solid hypoechoic heterogeneous nodule in the lower pole (0.73 x 0.63 cm) 1
• Bilateral reactive lymph nodes are present with internal echogenic hilum 1

Management Algorithm

Step 1: Diagnostic Workup

• Perform ultrasound-guided FNA of the complex mass in the left lobe (TR 3) as the primary next step 2, 1
• Measure serum TSH to evaluate thyroid function 1
• Consider FNA of the solid nodule in the right lobe if it has suspicious sonographic features 1

Step 2: Based on FNA Results

• If FNA is benign (Bethesda II):

  • For the complex mass ≥2 cm with solid component, follow up with ultrasound in 6-12 months 3
  • Consider thermal ablation if the nodule causes clinical symptoms or cosmetic concerns 2

• If FNA is indeterminate (Bethesda III or IV):

  • Consider molecular testing (BRAF/RAS, TERT, PIK3CA, TP53) to assist in diagnosis 2, 1
  • Consider surgical consultation if molecular testing suggests malignancy 1

• If FNA is suspicious or positive for malignancy (Bethesda V or VI):

  • Proceed to total thyroidectomy with or without central neck dissection depending on risk factors 2
  • Consider therapeutic neck dissection if suspicious lymph nodes are identified 2

Important Considerations

• The complex mass in the left lobe requires immediate attention due to its:

  • Size (>2 cm) 3
  • Complex/mixed echogenicity with solid component 4
  • Internal vascularity 1

• Mixed echoic nodules with >50% solid component have a higher malignancy rate (7.4%) compared to those with <50% solid component (2.2%) 4

• Eccentric placement of the solid component and presence of microcalcifications significantly increase the risk of malignancy in partially cystic nodules 4

• The small cyst in the right lobe (0.35 x 0.28 cm) is likely benign and does not require FNA due to its small size 1

• The solid nodule in the right lobe (0.73 x 0.63 cm) is below the typical 1 cm threshold for routine FNA unless it has suspicious features 2, 1

Pitfalls to Avoid

• Do not ignore the complex mass in the left lobe based solely on the presence of reactive lymph nodes, as metastatic papillary thyroid carcinoma can present with cystic cervical lymph nodes 5

• Do not assume benignity based on normal thyroid function, as both benign and malignant nodules can be functionally normal, hyperfunctioning, or hypofunctioning 6

• Do not rely on a single FNA if the initial result is non-diagnostic, as cystic or complex nodules may require repeat sampling 1, 5

• Remember that neither FNA nor core needle biopsy can definitively distinguish follicular adenoma from follicular carcinoma 2, 1