Multinodular goiter (MNG) is the most common thyroid pathology, characterized by the presence of multiple nodules in the thyroid gland. Prevalence varies between 5-50% depending on the degree of iodine deficiency and increases with age. Nodules may show various histological patterns including colloid, adenomatous hyperplasia, cystic degeneration, hemorrhage, and fibrosis. Most patients are euthyroid, but autonomously functioning nodules may develop in long-standing MNG, evolving into toxic multinodular goiter. Dominant nodule assessment should be performed according to ACR TI-RADS — as there is a 5-10% malignancy risk in the setting of MNG.
Age Range
30-70
Peak Age
50
Gender
Female predominant
Prevalence
Very Common
Multinodular goiter develops from heterogeneous proliferation of thyroid follicular cells under the influence of TSH stimulation and various growth factors. Iodine deficiency is the most important trigger — inadequate iodine intake reduces T3/T4 synthesis and compensatory TSH increase stimulates thyroid growth. However, follicular cells respond to TSH heterogeneously rather than homogeneously — some follicles proliferate faster, some undergo cystic degeneration, some acquire autonomous function. Over time, this heterogeneous growth creates multiple nodules. Hemorrhage, calcification, fibrosis, and colloid accumulation may develop within nodules. On imaging, this heterogeneity is reflected as multiple nodules with different echogenicity and density, cystic components, and calcifications. The spongiform pattern (multiple microcystic areas) reflects colloid accumulation and is a strong indicator favoring benignity.
Honeycomb-like pattern formed by multiple microcystic areas comprising more than 50% of the nodule volume. Has 99.7% specificity for benignity and is classified as ACR TI-RADS TR2. Reflects colloid accumulation and essentially excludes malignancy.
Multiple nodules are seen in the thyroid gland. Nodules have different sizes, echogenicity, and internal structures — some isoechoic solid, some hyperechoic (colloid-rich), some cystic or mixed. Gland dimensions are increased (goiter). Each nodule should be independently evaluated according to ACR TI-RADS. Dominant or suspicious nodules (hypoechoic, irregular margin, microcalcification, taller-than-wide) are candidates for FNA.
Report Sentence
Thyroid gland is enlarged with multiple nodules in both lobes. Dominant nodule in the [right/left] lobe measures ... mm and is assessed as ACR TI-RADS TR.... Consistent with multinodular goiter.
Spongiform (sponge-like/honeycomb) pattern formed by multiple microcystic areas within the nodule is seen. Each microcyst is 1-2 mm in diameter, anechoic, and round. Microcysts comprise more than 50% of the nodule volume. This pattern scores 0 points in ACR TI-RADS and is classified as TR2 (not suspicious) — it has high specificity (99.7%) for benignity.
Report Sentence
Nodule measuring ... mm in the [right/left] thyroid lobe shows spongiform pattern (honeycomb appearance), consistent with benign colloid nodule (ACR TI-RADS TR2).
On Doppler US, MNG nodules typically show peripheral (capsular) vascularity pattern — thin vascular ring around the nodule. Intranodular vascularity is low or moderate. This peripheral pattern is typical for adenomatous nodules. Increased intranodular vascularity or chaotic vascular pattern raises suspicion for malignancy and requires further evaluation.
Report Sentence
Doppler examination shows predominantly peripheral vascularity pattern in the nodules, consistent with benign adenomatous nodule.
Contrast-enhanced CT evaluates retrosternal extension of large multinodular goiter. Intrathoracic extension is seen as a mass in the anterior mediastinum in relation to the trachea and great vessels. Tracheal narrowing and deviation can be measured. Nodules show heterogeneous enhancement — solid areas enhance while cystic/necrotic areas do not. Coarse calcifications are common. CT is superior to US in demonstrating the extent of retrosternal extension, degree of tracheal compression, and vascular relationships, and is required for surgical planning.
Report Sentence
Multinodular goiter shows retrosternal extension with intrathoracic component measuring ... cm. Trachea is narrowed to ... mm and deviated to the [right/left]. Evaluation for surgical planning is recommended.
Tc-99m pertechnetate scintigraphy shows heterogeneous uptake in the thyroid gland. 'Hot' (increased uptake) and 'cold' (decreased uptake) areas coexist. Autonomously functioning nodules appear hot while cystic, degenerated, or fibrotic nodules appear cold. In toxic multinodular goiter, dominant hot nodule(s) may cause suppression of surrounding parenchyma. Scintigraphy is used in patients with low TSH to identify hot (autonomous) nodules and to distinguish cold nodules that may carry malignancy suspicion.
Report Sentence
Tc-99m scintigraphy shows heterogeneous uptake in the thyroid gland with an increased uptake (hot) nodule measuring ... mm in the [right/left] lobe and decreased uptake (cold) areas. Consistent with multinodular goiter.
T2-weighted MRI shows multiple nodules with different signal intensities in the thyroid gland. Cystic/colloid components show T2 hyperintensity, solid components intermediate-low signal, hemorrhagic areas T1 hyperintensity. MRI is an alternative to CT especially for evaluation of retrosternal extension and vascular relationships (non-iodinated contrast, no radiation). On DWI, suspicious solid nodules can be evaluated for diffusion restriction.
Report Sentence
MRI shows multiple nodules with different T1/T2 signal characteristics in the thyroid gland, consistent with multinodular goiter. Retrosternal extension [present/absent].
Criteria
Normal TSH, T3 and T4 levels. Thyroid function is preserved. Most common form (70-80%). Nodules are not functionally autonomous.
Distinct Features
Normal or mildly heterogeneous uptake on scintigraphy. No hot nodules. Nodules show benign TI-RADS scores on US. No treatment needed (if no compression).
Criteria
Low TSH, elevated T3/T4. One or more autonomously functioning nodules are present. Usually develops on the background of long-standing nontoxic MNG. More common in elderly patients.
Distinct Features
One or more hot (increased uptake) nodules with suppression of surrounding parenchyma on scintigraphy. Requires I-131 treatment or surgery. Risk of cardiovascular complications (AF, heart failure).
Criteria
50% or more of the goiter extends below the thoracic inlet. Seen in 5-15% of large MNGs. Causes tracheal and esophageal compression. Requires surgery.
Distinct Features
Mass in anterior mediastinum on CT, tracheal narrowing and deviation. MRI alternative (no radiation). Surgical approach (cervical vs sternotomy) determined by extent of extension.
Distinguishing Feature
In Hashimoto thyroiditis, pseudonodules and inflammatory nodules are seen accompanying diffuse heterogeneous parenchyma. Anti-TPO is elevated. In MNG, distinct nodules are well-defined, parenchyma between them is more homogeneous, and autoimmune markers are usually negative.
Distinguishing Feature
Papillary carcinoma may develop in the setting of MNG (5-10% risk). Suspicious findings: markedly hypoechoic solid nodule, microcalcifications, irregular margin, taller-than-wide shape, and increased intranodular vascularity. Benign MNG nodules are isoechoic/hyperechoic, smooth-bordered, and show peripheral vascularity.
Distinguishing Feature
Follicular adenoma appears as a solitary, well-defined, isoechoic/hypoechoic nodule surrounded by a thin halo. Unlike MNG, it is usually a solitary nodule. May be indistinguishable from a dominant nodule within MNG on US — FNA required (follicular lesion cytology).
Urgency
routineManagement
surveillanceBiopsy
NeededFollow-up
12-monthThe key point in multinodular goiter management is evaluation of dominant nodules according to ACR TI-RADS and performing FNA when indicated. A 5-10% malignancy risk exists in the setting of MNG. Nontoxic asymptomatic MNG requires clinical and US follow-up (annual). Antithyroid drugs, I-131, or surgery are applied for toxic MNG. Retrosternal extension or significant compressive symptoms (tracheal narrowing >50%, dysphagia, dyspnea) are surgical indications. Levothyroxine suppression therapy is no longer recommended (unfavorable side effect/benefit ratio). In patients with low TSH, scintigraphy should be performed to differentiate hot/cold nodules.
Multinodular goiter is usually benign but each nodule should be separately evaluated by TI-RADS. Surgery may be needed for compressive symptoms (dysphagia, dyspnea). Toxic MNG may develop in autonomously functioning nodules. Malignancy risk is equivalent to solitary nodule (5-10%).