They are often surrounded by an outer surface (fibrous sheath of connective tissue) or stay contained within the epithelium.

Benign tumor growth causes a mass effect that can compress neighboring tissues.

Benign tumors are very diverse; they may be asymptomatic or may cause specific symptoms, depending on their anatomic location and tissue type.

This growth can cause compression of local tissues or organs, leading to many effects, such as blockage of ducts, reduced blood flow (ischaemia), tissue death (necrosis) and nerve pain or damage.

[11] Cowden syndrome is an autosomal dominant genetic disorder characterized by multiple benign hamartomas (trichilemmomas and mucocutaneous papillomatous papules) as well as a predisposition for cancers of multiple organs including the breast and thyroid.

[12][13] Bannayan–Riley–Ruvalcaba syndrome is a congenital disorder characterized by hamartomatous intestinal polyposis, macrocephaly, lipomatosis, hemangiomatosis and glans penis macules.

[11][14] Proteus syndrome is characterized by nevi, asymmetric overgrowth of various body parts, adipose tissue dysregulation, cystadenomas, adenomas, vascular malformation.

[18] Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder caused by mutations in the genes TSC1 and TSC2.

This disorder presents with many benign hamartomatous tumors including angiofibromas, renal angiomyolipomas, and pulmonary lymphangiomyomatosis.

[19][20][21] Von Hippel–Lindau disease is a dominantly inherited cancer syndrome that significantly increases the risk of various tumors.

The VHL protein (pVHL) is involved in cellular signaling in oxygen starved (hypoxic) cells.

[22] Benign tumors of bone can be similar macroscopically and require a combination of a clinical history with cytogenetic, molecular, and radiologic tests for diagnosis.

Local growth can cause destruction of neighboring cortical bone and soft tissue, leading to pain and limiting range of motion.

[citation needed] Lipomas are benign, subcutaneous tumors of fat cells (adipocytes).

They are usually painless, slow-growing, and mobile masses that can occur anywhere in the body where there are fat cells, but are typically found on the trunk and upper extremities.

[24] The main treatment for lipomas is surgical excision, after which the tumor is examined with histopathology to confirm the diagnosis.

[24] The prognosis for benign lipomas is excellent and recurrence after excision is rare, but may occur if the removal was incomplete.

[27] Benign tumors will grow in a contained area usually encapsulated in a fibrous connective tissue capsule.

[32] Tumors are formed by carcinogenesis, a process in which cellular alterations lead to the formation of cancer.

Multistage carcinogenesis involves the sequential genetic or epigenetic changes to a cell's DNA, where each step produces a more advanced tumor.

Promotion is the clonal expansion (repeated division) of this transformed cell into a visible tumor that is usually benign.

Following promotion, progression may take place where more genetic mutations are acquired in a sub-population of tumor cells.

[36] Hamartomas are a group of benign tumors that have relatively normal cellular differentiation but exhibit disorganized tissue organization.

[19] Exceptions to the nomenclature rules exist for historical reasons; malignant examples include melanoma (a cancer of pigmented skin cells, or melanocytes) and seminoma (a cancer of male reproductive cells).

[36] Benign tumors typically need no treatment unless if they cause problems such as seizures, discomfort or cosmetic concerns.

[38] Benign skin tumors are usually surgically resected but other treatments such as cryotherapy, curettage, electrodesiccation, laser therapy, dermabrasion, chemical peels and topical medication are used.