Which CT finding in lung adenocarcinoma in situ (previously bronchioloalveolar carcinoma) is considered the hallmark of lepidic growth pattern?
- A Spiculated mass with pleural tail sign
- B Cavitation with air-crescent sign
- C CT angiogram sign — visibility of pulmonary vessels through the consolidation ✓
- D Peribronchovascular consolidation with bronchus sign
Correct answer: C. CT angiogram sign — visibility of pulmonary vessels through the consolidation
Explanation
The CT angiogram sign refers to the visibility of pulmonary blood vessels through an area of airspace consolidation, and it is characteristic of adenocarcinoma with lepidic growth pattern (former BAC). The tumour cells spread along alveolar walls without destroying the architecture, preserving vascular visibility and creating the 'angiogram sign'. Cavitation with air-crescent indicates angioinvasive aspergillosis or squamous cell carcinoma. Spiculated masses with pleural tails are features of adenocarcinoma but not specific to lepidic pattern.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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