Cervical Lymphadenopathy in Children: Ultrasound Criteria for Reactive and Suspicious Nodes
When assessing cervical lymphadenopathy in children, the key principle is prioritizing morphology over size. A small round node without a hilum warrants greater concern than a large, elongated node with preserved hilum.
Benign (Reactive) Ultrasound Features
According to LN-RADS criteria (Validated Consensus Answers, Medtrain, 2026), features characteristic of reactive/benign nodes (LN-RADS 1–2) include:
- Preserved clear hyperechoic fatty hilum
- Elongated shape — ratio of long axis to short axis (L/S) > 2
- Uniform thin cortical layer (< 3 mm)
- Normal hilar blood flow pattern on color Doppler
Vascularity Assessment by Adler Classification
The Adler classification describes vascularity on color Doppler/power Doppler and applies to lymph nodes. Both the degree and type of blood flow are important:
| Blood Flow Type | Interpretation |
|---|---|
| Hilar (vascular pedicle) — vessels enter through the hilum, branching centripetally | Characteristic of reactive/benign nodes |
| Peripheral/mixed — vessels at capsule periphery or chaotic pattern | Raises suspicion for metastasis or lymphoma |
| Avascular | May occur with necrosis (tuberculosis, metastasis with breakdown) |
Adler grades: 0 — no blood flow detected; I — single vessel; II — few vessels (1–3 foci), predominantly in the hilum; III — marked vascularity throughout the node. Adler grade is an ancillary criterion assessed together with shape, Solbiati index (L/S), echogenicity of hilum, and cortical hypertrophy.
Suspicious Features and LN-RADS Categorization
Loss of benign features (absent hilum, round shape, focal/eccentric cortical thickening, peripheral vascularity) places the node in higher risk categories:
| Category | Interpretation |
|---|---|
| LN-RADS 0 | Incomplete assessment, additional imaging required |
| LN-RADS 1 | Normal / no pathologic lymph nodes |
| LN-RADS 2 | Benign features, malignancy unlikely (< 2%) |
| LN-RADS 3 | Probably benign, low risk (~2%) |
| LN-RADS 4 | Suspicious, moderate/high risk (>10%): cytologic verification required |
| LN-RADS 5 | High likelihood of malignancy (>50%): biopsy indicated |
| LN-RADS 6 | Histologically proven involvement (surveillance) |
Clinical Context and Additional Tools
Clinical context is mandatory: the same node in a healthy child and in a patient with confirmed lymphoma or post-treatment is assessed differently. Elastography is not part of the basic LN-RADS criteria but is used in practice — a stiff node on strain/SWE increases suspicion.
Frequently asked questions
What axis ratio indicates a benign node?
An elongated shape with a ratio of long axis to short axis (L/S, Solbiati index) > 2 is a benign feature.
What cortical thickness is considered normal?
A uniform thin cortical layer < 3 mm is a benign feature; focal or eccentric thickening should not be present.
What blood flow pattern raises suspicion for malignancy?
Peripheral or mixed blood flow pattern (vessels at the capsule periphery or chaotic) raises suspicion for metastasis or lymphoma. Hilar pattern is characteristic of reactive nodes.
Is node size or morphology more important?
Morphology is more important. LN-RADS emphasizes morphology rather than size alone: a small round node without a hilum warrants greater concern than a large elongated node with preserved hilum.
What does an avascular node on color Doppler indicate?
An avascular node may occur with necrosis — tuberculosis or metastasis with breakdown.