skip to main content

PET False Positive Nodes — SCE Medical Oncology MCQ

Instant feedback + full explanation. One question, done properly.

EasyLung CancerPET False Positive NodesSCE Medical Oncology

A 58-year-old man with NSCLC has a PET-CT for staging showing high SUVmax in the primary tumour and mediastinal nodes. The SUVmax of a mediastinal node is 5.8. Does this confirm N2 disease?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — No — false-positive PET in mediastinal nodes occurs in ~15-25% (reactive/inflammatory nodes); tissue confirmation (EBUS-TBNA or mediastinoscopy) is REQUIRED before classifying as N2, as this affects resectability and treatment decisions

PET-CT has excellent sensitivity (~90%) but imperfect specificity (~80-85%) for mediastinal staging in NSCLC. False-positive FDG uptake occurs with: reactive lymphadenopathy, granulomatous disease (sarcoidosis, TB), post-obstructive pneumonitis and anthracosis. NICE NG122 mandates tissue confirmation of PET-positive mediastinal nodes (via EBUS-TBNA, mediastinoscopy or EUS-FNA) before classifying as N2/N3, as this determines whether curative surgery is offered.

Reference: NICE NG122; ESMO 2024 NSCLC; BTS Lung Cancer Staging