Chest ImagingHamartoma, pulmonary
the most common
benign pulmonary neoplasm and the third commonest cause of a
solitary pulmonary nodule. Hamartomas orginate in fibrous connective tissue beneath the mucous membrane of the
bronchial wall. They contain mixtures of connective tissue, epithelial-lined clefts, nests of
cartilage and variable amounts of bone, vessels, fat and smooth muscles.
Hamartomas occur mainly between the fifth and the sixth decade with an age range of 3070. Most patients are asymptomatic and the tumour is incidentally discovered on a chest radiograph as a solitary pulmonary nodule that typically grows slowly. Occasionally hamartomas may be endobronchial in location, producing obstructive symptoms (see bronchial stenosis).
Radiographically, hamartoma usually appears as a well-defined spherical nodule or mass generally less than 4 cm in diameter. Calcifications are frequent in large lesions. The classic popcorn appearance of the calcification suggests the presence of cartilage. Hamartomas may be diagnosed confidently on CT scans when the nodule is less than 2 cm in diameter, appearing spherical with a smooth contour and sharp outline and containing fat collection more or less associated with popcorn calcifications (Fig.1).
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CT scan in a patient with pulmonary hamartoma. There is a round smooth well-defined nodule containing popcorn calcification and a collection of fat.
(From Grenier P., Imagerie Thoracique de lAdulte. Flammarion, Paris, France, 1996, with permission.)
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Hamartoma, pulmonary, Fig.1 | |