Non-cancerous soft tissue tumours

A non-cancerous (benign) soft tissue tumour is a growth that does not spread (metastasize) to other parts of the body. Non-cancerous tumours are not usually life-threatening. They are typically removed with surgery and do not usually come back (recur).

There are many types of non-cancerous soft tissue tumours. They are grouped by the type of soft tissue where the tumour started.

Many non-cancerous soft tissue tumours start in the fat tissue of the body including the following.

Lipoma is the most common type of non-cancerous soft tissue tumour. It usually develops as a soft, painless lump that grows slowly. Less often, a lipoma may develop as a group of many lumps or abnormal areas. Most lipomas develop in the fat tissue just under the skin (subcutaneous). They are usually found in the trunk of the body and the limbs.

Lipoblastoma (also called lipoblastomatosis) develops in babies and young children. It is an unusual type of lipoma made up of immature fat cells.

Hibernoma tends to grow slowly. It usually develops in the chest (thorax). It can also develop in the trunk of the body, limbs and back of the abdomen (retroperitoneum).

Different non-cancerous tumours can develop in fibrous tissues.

Fibroma is a general term used to describe a group of non-cancerous tumours that start in the skin or fibrous soft tissues, such as tendons and ligaments. Fibromas are usually slow-growing tumours.

Elastofibroma is a rare non-cancerous tumour that grows slowly. Elastofibromas usually develop between the lower part of the shoulder blade and the chest wall. They tend to happen in older adults and are thought to be caused by repetitive manual tasks. These tumours can grow to 5 to 10 cm in diameter.

Superficial fibromatosis is when small non-cancerous tumours develop in the tissues of the hands, feet or penis. These tumours tend to grow slowly. Superficial fibromatosis is most common in a hand and is called palmar fibromatosis. When it happens in a foot, it is called plantar fibromatosis. When it happens in the penis, it is called penile fibromatosis. The tumours are more likely to develop in the feet or penis if they have already happened in the hands. They are likely to come back after they are removed.

Desmoid-type fibromatosis is a soft tissue tumour that is usually non-cancerous. It tends to come back after treatment and grow into (invade) nearby tissue. But it doesn’t spread to other parts of the body. It often starts in the arms, legs or abdomen.

Deep benign fibrous histiocytoma forms in the tissue deep under the skin usually in the legs or head and neck area. It is a slow-growing, painless lump. When a benign fibrous histiocytoma starts in the layers of the skin, it is often called a dermatofibroma.

Non-cancerous muscle tumours happen most often in smooth (involuntary) muscle. They may also develop in skeletal (voluntary) muscle.

Leiomyomas are non-cancerous tumours that develop in smooth muscle. They often happen as many painful lumps. Leiomyomas can start almost anywhere in the body but are most common in the gastrointestinal (GI) tract and uterus. (A leiomyoma that develops in the uterus is also called a fibroid.) These benign tumours may also develop deep in a limb and in the abdominal cavity or the back of the abdomen (retroperitoneum).

Rhabdomyoma is a rare non-cancerous tumour that starts in skeletal muscle.

Non-cancerous tumours of the blood and lymph vessels may also be called non-cancerous vascular tumours. Sometimes tumours are found around blood vessels (called perivascular tumours).

Hemangioma is a common non-cancerous soft tissue tumour caused by an abnormal buildup of blood vessels. Hemangiomas are found in the skin or internal organs. Many small hemangiomas go away on their own. If they are large or causing problems, they may be treated with laser surgery or drugs, such as steroids or beta blockers.

Glomus tumours develop around blood vessels usually under the skin of the fingers or in the hands, wrists and feet. They appear as a small bluish-red lump under the skin and can be quite painful. There is also a cancerous type of glomus tumour called malignant glomus tumour.

Lymphangioma develops in the lymph vessels. Lymphangiomas can happen at any age, but they are often present at birth or develop in children under the age of 2 years. It usually develops in the head and neck area. Lymphangiomas grow slowly and look like a soft, doughy mass. They can grow quite large.

There are nerves (nerve tissue) throughout the body. Non-cancerous tumours can develop anywhere along these nerves.

Neurofibroma is a small, slow-growing lump in the nerves just under the skin or in other parts of the body. Neurofibromas usually develop in adults in their 30s. People with neurofibromatosis type 1 often develop many neurofibromas.

Schwannoma is a slow-growing tumour that starts in Schwann cells. These cells make up the protective covering (sheath) around the nerves. These tumours often develop in the head and neck, in the limbs and around the spine along the back of the abdomen. Schwannomas happen most often in adults 20 to 50 years old.

Granular cell tumour is thought to develop in nerve tissue. It usually develops in the mouth, but the tumours can also happen almost anywhere in the body.

Tumours are usually named and grouped based on the type of normal cells the tumour cells look like under a microscope. Some non-cancerous tumours have not been linked to a type of soft tissue cell. Doctors don’t know what type of cell these tumours started from.

Myxoma is a rare non-cancerous tumour that is usually found in the large muscles of a limb. But it does not really develop from muscle cells. These tumours make large amounts of mucus-like material, which distinguishes them from other tumours.

Perivascular epithelioid cell tumours (PEComas) seem to start in the cells of the walls of blood vessels, but experts don’t know for sure. Most PEComas are non-cancerous, but they can be cancerous in rare cases.