MPUS of Thyroid Nodules Bethesda III–IV and Cervical Lymph Nodes: EFSUMB 2026

Clinical Task Part II EFSUMB 2026

The second part of the EFSUMB 2026 guidelines on MPUS of thyroid nodules addresses situations where standard nodule description is insufficient: indeterminate cytology, multinodular goiter, suspicion of extrathyroidal extension, target selection for biopsy, and staging of cervical lymph nodes. The practical purpose of MPUS is not to "replace" biopsy but to reduce uncertainty before repeat FNA, core-needle biopsy, surgery, or dynamic observation.

The multiparametric approach includes grayscale analysis, color or power Doppler, elastography, and in specific tasks, contrast-enhanced ultrasound. Interpretation should be integral: an isolated feature, including high stiffness, is not an independent diagnosis of cancer.

What Constitutes MPUS in Thyroid Nodules

The basic layer is B-mode: nodule composition, echogenicity, contour, shape, calcifications, capsular contact, and relationship with the trachea, esophagus, muscles, and neurovascular bundle. The second layer is vascularization: the type and distribution of blood flow help select the viable part of the nodule for biopsy, especially in cystic-solid transformation and after previous interventions.

The third layer is elastography. EFSUMB emphasizes that elastography is useful as a component of risk stratification, but a universal stiffness threshold in kPa for all devices, modes, and populations should not be used as an absolute criterion. The protocol should specify the method: strain elastography or shear-wave elastography, measurement quality, and the area where the assessment was performed.

Classes and Scenarios Where MPUS Changes Tactics

Bethesda III–IV: How to Use MPUS

In Bethesda III–IV, the main error is interpreting elastography as an "arbiter" between benign and malignant processes. EFSUMB suggests a different approach: reconsider the entire nodule phenotype. If low-risk grayscale features align with a soft elastographic pattern and there are no suspicious lymph nodes, MPUS supports a conservative approach, repeat cytology, or observation depending on the clinical context.

If the nodule has high-risk features—marked hypoechogenicity, irregular or infiltrative contour, taller-than-wide shape, microcalcifications, suspicious capsular contact—elastography should not "reassure." In such a situation, MPUS helps select the most informative target: a solid hypoechoic area, a zone with disrupted contour, or an area with heterogeneous stiffness, avoiding necrosis, coarse calcification, and cystic components.

Elastography: Strengths and Limitations

Elastography is especially useful in solid nodules when it is necessary to increase confidence in risk stratification. A stiff nodule against a suspicious B-mode background strengthens the case for biopsy or surgical route. A soft nodule with a benign grayscale phenotype reduces the likelihood of an aggressive decision but does not negate clinical indications.

Limitations are fundamental: large calcifications, pronounced fibrosis, cystic-solid structure, deep location, probe compression, and varying device algorithms distort the result. Therefore, the conclusion should not simply state "the nodule is stiff." It is more accurate to specify the method, quality of the map, localization of the stiff area, and correlate the result with EU-TIRADS and cytology.

Multinodular Goiter: Which Nodule to Biopsy

In multinodular goiter, MPUS is needed for prioritization, not for biopsying "the largest" nodule. The nodule with the most suspicious phenotype is chosen: unfavorable morphology in B-mode, suspicious capsular area, pathological stiffness, discrepancy between size and local invasion, and a nodule anatomically linked to a suspicious lymph node.

If several nodules have similar risk, biopsy guidance is oriented towards the area where the likelihood of obtaining diagnostic material is highest: solid tissue, viable vascularized part, area without coarse acoustic shadow. Doppler is important here not for cancer diagnosis per se, but for safe and informative access.

Extrathyroidal Extension

Before surgery, ultrasound should answer not only the question "is there cancer," but also "are there signs of extension beyond the gland." Capsule discontinuity, extensive contact of the nodule with the capsule, contour bulging, involvement of anterior muscles, trachea, esophagus, recurrent zone, carotid artery, and jugular vein are assessed. MPUS helps distinguish simple adjacency from infiltrative behavior, but in case of doubt, the conclusion should be descriptive rather than categorical.

Suspicion of extrathyroidal extension increases the significance of complete neck mapping. Even a small primary focus with an aggressive local phenotype requires careful search for metastatic lymph nodes.

Ultrasound-Guided Biopsy

According to EFSUMB, ultrasound guidance is the standard for precise biopsy of complex nodules and lymph nodes. MPUS before puncture clarifies trajectory, vascular risks, and sampling area. In cases of repeatedly non-informative cytology or heterogeneous tumors, discussing core-needle biopsy is advisable if it is accepted in the local pathway and technically feasible.

For lymph nodes with suspected metastasis, targeted FNA is performed; in differentiated thyroid cancer, the informativeness is increased by testing thyroglobulin in needle washout, and in suspected medullary cancer, calcitonin in washout. These tests do not replace morphology but help confirm the thyroid origin of the metastasis.

Cervical Lymph Node Staging

In neck staging, lymph node size is secondary. Suspicious features include rounding, loss of the echogenic hilum, microcalcifications, cystic transformation, peripheral or chaotic blood flow, hyperechogenicity of the cortical layer resembling thyroid tissue, focal cortical thickening, and heterogeneity. Cystic changes and microcalcifications are particularly specific if they are combined with known or suspected papillary cancer.

Mapping should be systematic: central compartment, lateral compartments on both sides, and supraclavicular zones. The conclusion must indicate the side, level or anatomical area, sizes, key suspicious features, and which lymph node is recommended for biopsy. This is critical for distinguishing N1a from N1b and for planning the extent of surgery.

How to Formulate a Conclusion

An optimal MPUS conclusion should not be a set of disparate features. A practically useful structure: ultrasound risk category of the nodule, elastography result with limitations, signs or absence of extrathyroidal extension, lymph node status, recommended biopsy target, and type of intervention. For Bethesda III–IV, it is important to explicitly state whether MPUS changes the risk compared to the initial protocol and whether there are grounds for repeat biopsy of another area.

A short formula for the physician: in indeterminate cytology, MPUS enhances decision quality but does not create an independent morphological diagnosis; in suspicious lymph nodes, it should conclude with precise mapping and targeted verification.