Cancerous tumours of the eye

A cancerous tumour of the eye can grow into nearby tissue and destroy it. The cancer can also spread (metastasize) to other parts of the body. Cancerous tumours are also called malignant tumours. Cancerous tumours of the eye are rare.

Melanoma of the eye is the most common type of eye cancer in adults. It develops from cells called melanocytes. Melanocytes make melanin, the substance that gives colour to the eyes, skin and hair.

Melanoma of the eye most often starts in the eyeball. If it starts in melanocytes in the uvea, it is called uveal melanoma. If it starts in melanocytes in the conjunctiva, it is called conjunctival melanoma. Both uveal melanoma and conjunctival melanoma are types of intraocular melanoma. (Intraocular means “within the eyeball.”) Uveal melanoma is much more common than conjunctival melanoma.

Melanoma of the eye can sometimes start in melanocytes in the orbit, which is part of the eye socket. This is called orbital melanoma.

When melanoma starts in the eyelid, it is considered melanoma of the skin.

Uveal melanoma (a type of intraocular melanoma) is the most common type of cancerous tumour of the eye in adults. Uveal melanomas make up more than 80% of all cancerous tumours of the eye.

Uveal melanomas are usually grouped by what part of the eye the tumour starts in.

Anterior uveal melanoma begins in the iris at the front of the eye. These tumours are usually slower growing and less likely to spread (metastasize).

Posterior uveal melanoma begins in the choroid or ciliary body. These structures are behind the front part of the eye. Because they can’t be seen, posterior uveal melanomas are typically found at a more advanced stage than anterior uveal melanomas. These tumours are also more likely to metastasize. Most of the time, uveal melanoma starts in the choroid.

Using a system called modified Callendar classification, posterior uveal melanoma can be classified by the appearance of the melanocytes in the tumour:

• spindle cell melanoma – 90% or more of the cells are spindle cells (including spindle A cells and spindle B cells), which are long and thin
• epithelioid melanoma – 90% or more of the cells are epithelioid cells, which are round
• mixed-cell type melanoma – made up of a mixture of spindle and epithelioid cells

Lymphoma of the eye is the second most common type of eye cancer. It begins in lymphocytes of the eye. A lymphocyte is a type of white blood cell that fights viruses, bacteria, foreign substances or abnormal cells (including cancer cells). In most cases, lymphoma of the eye is a type of non-Hodgkin lymphoma called diffuse large B-cell lymphoma (DLBCL).

Lymphoma of the eye can be grouped by the part of the eye that the cancer started in.

Orbital adnexal lymphoma begins in the eye socket or adnexal structures, including the conjunctiva, eyelid and tear (lacrimal) gland. It is the most common cancer of the eye socket and adnexal structures.

Intraocular lymphoma begins in the vitreous humour, uvea, retina or optic nerve. It is sometimes called ocular lymphoma or vitreoretinal lymphoma (VRL). Less than 1% of cases of eye cancer are intraocular lymphoma.

Squamous cell carcinoma (SCC) of the eye starts in squamous cells of the conjunctiva. Squamous cells are flat, thin cells that form the surface or lining of many parts of the body. This type of eye cancer is often called conjunctival SCC or SCC of the conjunctiva. SCC develops from conjunctival intraepithelial neoplasia (CIN) that has grown into the connective tissue layer of the conjunctiva.

SCC of the eye can be classified by the appearance of the cancer cells in the tumour. The cancer cells can be spindle (long and thin) or epithelioid (round).

Squamous cell carcinoma can also affect the eyelid. When this happens, it is considered to be a type of non-melanoma skin cancer.

Retinoblastoma is the most common eye cancer in children. It rarely occurs in adults.

Find out more about retinoblastoma.

The following cancerous tumours of the eye are rare:

Basal cell carcinoma (BCC) is a type of non-melanoma skin cancer. It usually starts in the eyelid and is the most common type of cancer of the eyelid.

Intraocular medulloepithelioma develops in the ciliary body. It most often affects children.

Orbital rhabdomyosarcoma is a type of soft tissue sarcoma that starts in the eye socket. It can start in the muscles that move the eye and it most often affects children. Find out more about rhabdomyosarcoma.

Sebaceous carcinoma is a type of cancer that develops in the oil glands (sebaceous glands) of the skin. It most often occurs on the upper eyelid close to the eyelash line.