Hamartoma

A hamartoma is a mostly benign, local malformation of cells that resembles a neoplasm, or tumor, of the local tissue, but is usually caused by an overgrowth of multiple aberrant cells rather than by descent from a single mutated cell. This distinguishes most hamartomas from typical benign tumors, which are monoclonal, though some hamartomas do show clonal chromosomal changes acquired through later somatic mutation. Hamartomas are generally slow-growing or self-limiting, are usually caused by an underlying genetic syndrome that affects the normal cycle of cell development, and are often asymptomatic, being discovered only incidentally during imaging performed for an unrelated reason. They can occur throughout the body in a wide range of tissues, and are diagnosed using methods such as chest x-ray, CT scan, MRI, ultrasound, or bronchoscopy depending on their location. Hamartomas are associated with several recognized genetic syndromes, including tuberous sclerosis, Cowden syndrome, PTEN hamartoma tumor syndrome, and Peutz-Jeghers syndrome, and with genes including SMAD4, PTEN, STK1, and BMPR1A. The name comes from the Greek word hamartia, meaning error, and was introduced by the pathologist Eugen Albrecht in 1904.