Radiography of lymph nodes

Cervical lymphadenopathy

The assessment of cervical lymph nodes depends on the type of pathological process. In Hodgkin lymphoma (HL), cervical lymphadenopathy is detected in the vast majority of initial manifestations (up to 80%). A characteristic feature of HL is the sequential spread to adjacent lymphatic drainage basins—for example, from the internal jugular vein to the deep cervical nodes. If the involvement affects both sides of the neck or the supraclavicular regions, there is a high probability of subdiaphragmatic lymph node involvement.

In non-Hodgkin lymphoma (NHL), cervical nodes are affected less frequently, but Waldeyer's ring is often involved (which is considered a lymph node for staging purposes). Dissemination usually lacks a clear sequence (non-contiguous groups are affected), and central necrosis within nodes is almost absent, which helps differentiate NHL from squamous cell carcinoma metastases. Contrast-enhanced CT, MRI, or PET/CT are optimal for detecting non-palpable nodes and monitoring treatment.

Intrathoracic lymphadenopathy

The prevalence of mediastinal node involvement varies significantly:

• Hodgkin lymphoma: mediastinal nodes are affected in 60–85% of cases. Typically, prevascular and paratracheal groups (84%) are involved, along with the lung huli and subcarinal nodes. Pericardial nodes are rarely affected at initial diagnosis. Involvement of multiple groups simultaneously is characteristic.
• Non-Hodgkin lymphoma: intrathoracic nodes are altered in only 25–40% of cases. Half of the patients have isolated involvement of a single group only (often upper mediastinal — 35%).

In both types of lymphoma, large nodal conglomerates can form in the anterior mediastinum, often merging with the thymus gland. CT and PET/CT can detect involvement even when the plain chest radiograph appears normal.

Abdomen and retroperitoneum

At initial diagnosis of NHL, retroperitoneal lymph nodes are affected much more frequently (up to 55%) than in HL (25–35%). Involvement of mesenteric nodes is also typical for NHL (more than 50% vs. less than 5% in HL). The porta hepatis and spleen are more commonly affected in NHL.

In HL, spread occurs in a predictable pattern along lymphatic vessels from the diaphragm to retrocrural nodes and further to the celiac trunk. Diagnosis in the celiac trunk area is difficult because HL may present with lymph node involvement without size changes.

Role of CT and PET in lung cancer staging

Lymph node evaluation is a key step in intrathoracic staging. Radiography, CT, and 18F-FDG PET/CT are the fundamental methods.

CT has high sensitivity for detecting node enlargement, but low specificity because hyperplasia can be reactive (e.g., due to atelectasis or inflammation). Therefore, histological confirmation (biopsy) is mandatory before denying surgery due to suspected metastases. PET/CT better differentiates malignant and benign nodes and detects occult metastases, but positive PET results also require biopsy. Negative findings on both methods (no enlargement on CT, negative PET) make nodal involvement extremely unlikely.

Class and exam questions

What else to study on this topic

• Radiological evaluation of pleural effusion
• Extrathoracic staging of lung cancer
• Differential diagnosis of mediastinal masses
• Fibrosing mediastinitis: focal and diffuse types
• Acute mediastinitis: causes and CT findings

Other topics in the «Chest Radiology» section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.