A 35-year-old woman undergoes staging investigations for newly diagnosed Hodgkin lymphoma. Which is the most common site of involvement at presentation in Hodgkin lymphoma?

Explanation

## Sites of Involvement in Hodgkin Lymphoma **Key Point:** The **cervical and mediastinal lymph nodes** are the most common sites of involvement at presentation in Hodgkin lymphoma, occurring in approximately 80% of patients. ### Frequency of Nodal Involvement at Presentation | Site | Frequency at Presentation | Notes | |------|--------------------------|-------| | **Cervical nodes** | ~80% | Most common single site; often the presenting symptom | | **Mediastinal nodes** | ~60% | Especially in nodular sclerosis subtype; may cause respiratory symptoms | | **Axillary nodes** | ~30% | Less common than cervical | | **Inguinal nodes** | ~25% | More common at relapse than at presentation | | **Splenic involvement** | ~25% | Detected on imaging; rarely symptomatic | | **Hepatic involvement** | ~10% | Indicates advanced disease; usually with splenic involvement | **High-Yield:** Hodgkin lymphoma shows a characteristic **orderly, contiguous spread** from one lymph node group to adjacent groups (unlike non-Hodgkin lymphoma, which is often random). This predictable pattern is why the **cervical and mediastinal nodes** — which are anatomically contiguous — are frequently involved together. ### Clinical Presentation Pattern **Clinical Pearl:** Patients typically present with **painless cervical lymphadenopathy** (often unilateral initially), which may be accompanied by a mediastinal mass discovered on routine chest imaging. The mediastinal involvement can cause: - Cough - Chest discomfort - Superior vena cava syndrome (in advanced cases) **Mnemonic:** **"Cervical-first, then down"** — Hodgkin tends to involve the cervical nodes first, then spread downward to mediastinal, axillary, and eventually inguinal nodes in a predictable fashion. ### Why Inguinal Nodes Are NOT Most Common Inguinal nodes are involved in only ~25% of patients at presentation. They become more frequent at **relapse** or in **advanced disease**, but are not the primary site of involvement. The orderly spread pattern means inguinal involvement usually occurs only after cervical and mediastinal disease is established.