← All patterns
Solitary pulmonary nodule
ChestCT / Radiograph
A single, rounded opacity ≤3 cm surrounded by aerated lung. Management is driven by malignancy probability from morphology, growth and smoking/age risk.
Differential
Infectious granuloma (healed TB / histoplasmosis)
common- •Central / diffuse / laminated (popcorn-like) calcification
- •Stable over ≥2 years
- •Smooth well-defined margin
Primary bronchogenic carcinoma
common- •Spiculated / lobulated margin
- •Growth on serial CT (or FDG-avid)
- •Upper-lobe predominance in a smoker
- •Part-solid / persistent ground-glass component (adenocarcinoma)
Hamartoma
less-common- •Popcorn (chondroid) calcification
- •Macroscopic fat within the nodule
- •Smooth margin, very slow growth
Solitary metastasis
less-common- •Known extrathoracic primary
- •Smooth well-defined round margin
- •Lower-lobe / peripheral location
Carcinoid tumour
rare- •Central endobronchial location with distal collapse
- •Avid homogeneous enhancement
- •Younger, often non-smoker
Arteriovenous malformation
rare- •Feeding artery and draining vein
- •Uniform enhancement matching the aorta
- •Association with hereditary haemorrhagic telangiectasia
Key discriminators
- •Calcification pattern (benign central/popcorn vs eccentric/absent)
- •Margin: smooth vs spiculated/lobulated
- •Growth rate on prior imaging (doubling time)
- •Presence of macroscopic fat (hamartoma)
- •FDG avidity on PET
Work-up / next steps
- 1.Retrieve any prior imaging to assess stability/growth
- 2.Apply Fleischner Society follow-up criteria by size and risk
- 3.PET-CT for indeterminate solid nodules ≥8 mm
- 4.Biopsy or resection if malignancy probability is high
References
- MacMahon H et al. Fleischner Society 2017 guidelines. Radiology.
- Radiopaedia: Solitary pulmonary nodule.
Educational clinical decision support only. This differential does not make a diagnosis, is not a medical device, and must never substitute for interpretation by a qualified radiologist correlated with the full clinical picture and prior imaging.