hamartomas

Hamartomas are benign, focal malformations that consist of an abnormal mixture of tissue elements normally found at the site of the lesion, arranged in a disorganized or haphazard way. They are not true neoplasms and do not represent cancer; rather, they are developmental overgrowths of mature tissues. Hamartomas should be distinguished from choristomas, in which normal tissues are present in an abnormal location.

The lungs are the most common site for hamartomas, with pulmonary hamartomas typically composed of cartilage, fat, connective tissue, and sometimes bone. On imaging, they are usually well circumscribed and solitary, and may show popcorn-like calcifications. Hamartomatous growths can occur in other organs as well, including the liver, kidneys, brain, and skin, where they likewise consist of mature tissue elements arranged abnormally.

Clinical presentation varies. Many hamartomas are asymptomatic and discovered incidentally during imaging for unrelated reasons. If a lesion is large or situated in a critical area, it can cause symptoms due to mass effect or, less commonly, bleeding. Diagnosis relies on imaging characteristics, with histopathologic confirmation obtained by biopsy or surgical excision when necessary to exclude malignancy or to clarify uncertain findings.

Management is typically conservative for asymptomatic lesions. Observation is common, while surgical excision or removal may be indicated for symptomatic lesions, diagnostic uncertainty, or when malignancy cannot be confidently excluded. The prognosis for hamartomas is generally excellent, as they do not metastasize and malignant transformation is rare. In certain genetic conditions, such as tuberous sclerosis, multiple hamartomatous lesions can occur in different organs, reflecting a broader predisposition to hamartoma formation.