bronchial hamartoma
Summary
Bronchial (pulmonary) hamartoma is the most common benign lung tumor, composed of disorganized mature tissue (cartilage, fat, smooth muscle, epithelium) native to the lung. Classic finding: peripheral 'coin lesion' with 'popcorn' calcification on chest imaging.
Detail
A hamartoma is a disorganized overgrowth of normal tissues at their normal site (vs. choristoma, which is normal tissue at an abnormal site). Pulmonary hamartomas typically present in middle-aged adults as an incidental, solitary, well-circumscribed peripheral nodule (1-4 cm) on chest X-ray or CT, with characteristic 'popcorn' calcification and intralesional fat (highly suggestive on CT). Histology shows a mix of mature hyaline cartilage, adipose tissue, smooth muscle, and entrapped respiratory epithelium. They are benign with negligible malignant potential and are usually only resected if diagnosis is uncertain or symptomatic. Carney triad (gastric GIST + pulmonary chondroma + extra-adrenal paraganglioma) involves pulmonary chondromas, not classic hamartomas.
Sources
- First Aid for USMLE Step 1 2024
- Robbins Basic Pathology 10th ed
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