Lesions/Condition: Pulmonary Hamartoma

Predisposing Factors:

Most commonly occurs in the fourth to fifth decade. Most common chromosomal abnormality involves the q13-q15 region of chromosome 12.

Symptoms:

Most patients presenting with peripheral pulmonary hamartomas are asymptomatic. When symptomatic, hemoptysis is the most common presenting symptom.

Discussion:

Pulmonary hamartomas are benign neoplasm with 90% arising within the lung parenchyma, and are usually in a peripheral location. They comprise approximately 5% of all solitary pulmonary nodules. Pulmonary Hamartomas contain cartilage surrounded by fibrous connective tissue with variable amounts of fat, smooth muscle, and seromucous glands. Approximately 30% contain calcium in the form of multiple clumps (‘popcorn’ calcification).

Generally, pulmonary hamartomas can be observed by CT alone. Indications for transthoracic biopsy or resection are rapid growth, a size greater than 2.5 cm, or new pulmonary symptoms.

Radiology:
   
Chest Radiographs:
Well-circumscribed, smoothly marginated solitary nodule without lobar predilection. Most pulmonary hamartomas are smaller than 4 cm in diameter. Calcification is visible in less than 10% of cases.

CT:
Well-circumscribed nodule with a smooth or lobulated border.
Composed entirely of fat, a mixture of fat and soft tissue, or fat and calcification. Calcification when present is in the form of multiple clumps of calcium dispersed throughout the lesion (“popcorn� calcification)