page_title: Hamartoma
section_title: Lung
hierarchical_section_title: Hamartoma / Diagnosis / Types / Lung
caption_attribution_description: LOWER RESPIRATORY TRACT: GROSS APPEARANCE OF PARENCHYMAL HAMARTOMA The surrounding lung falls away from the well-circumscribed mass, a typical feature of these lesions. The hamartoma shows a variegated yellow and white appearance, which corresponds respectively to fat and cartilage.
context_page_description: A hamartoma is a mostly benign, local malformation of cells that resembles a neoplasm of local tissue but is usually due to an overgrowth of multiple aberrant cells, with a basis in a systemic genetic condition, rather than a growth descended from a single mutated cell, as would typically define a benign neoplasm/tumor. Despite this, many hamartomas are found to have clonal chromosomal aberrations that are acquired through somatic mutations, and on this basis the term hamartoma is sometimes considered synonymous with neoplasm. Hamartomas are by definition benign, slow-growing or self-limiting, though the underlying condition may still predispose the individual towards malignancies.
  Hamartomas are usually caused by a genetic syndrome that affects the development cycle of all or at least multiple cells. Many of these conditions are classified as overgrowth syndromes or cancer syndromes. Hamartomas occur in many different parts of the body and are most often asymptomatic incidentalomas. Additionally, the definition of hamartoma versus benign neoplasm is often unclear, since both lesions can be clonal.
context_section_description: About 5–8% of all solitary lung nodules and about 75% of all benign lung tumors, are hamartomas. They almost always arise from connective tissue and are generally formed of cartilage, connective tissue, and fat cells, although they may include many other types of cells. The great majority of them form in the connective tissue on the outside of the lungs, although about 10% form deep in the linings of the bronchi. They can be worrisome, especially if situated deep in the lung, as it is sometimes difficult to make the important distinction between a hamartoma and a lung malignancy. An X-ray will often not provide a definitive diagnosis, and even a CT scan may be insufficient if the hamartoma lacks the typical cartilage and fat cells. Lung hamartomas may have popcorn-like calcifications on chest xray or computed tomography (CT scan).  
  Lung hamartomas are more common in men than in women, and may present additional difficulties in smokers. 
  Some lung hamartomas can compress surrounding lung tissue to a degree, but this is generally not debilitating and is often asymptomatic, especially for the more common peripheral growths. They are treated, if at all, by surgical resection, with an excellent prognosis: generally, the only real danger is the inherent possibility of surgical complications.
caption: Parenchymal hamartoma of the lung. The surrounding lung falls away from the well-circumscribed mass, a typical feature of these lesions. The hamartoma shows a variegated yellow and white appearance, which corresponds respectively to fat and cartilage.
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