Desmoplastic Melanoma, from the CureRays guide library.

Desmoplastic melanoma is an uncommon, often colorless form of melanoma that grows as a firm scar-like patch on sun-damaged skin and tends to creep along nerves — surgery is the main treatment, and unlike most melanomas it is notably responsive to radiation.

What it is.

Desmoplastic melanoma is an uncommon subtype of melanoma made up of spindle-shaped cells woven through dense, scar-like (fibrous) tissue. It usually appears on chronically sun-damaged skin — most often the head and neck — in older adults, and it can be easy to miss because it often lacks the dark pigment people associate with melanoma, showing up instead as a firm, flesh-colored or pink lump or a scar-like area. Two features set it apart from ordinary melanoma: it has a strong tendency to grow along nerves (perineural invasion), which can let it extend beyond what is visible, and it has a relatively low tendency to spread to lymph nodes when it is the 'pure' form. Because of the nerve-tracking habit and its location on the face, wide and complete surgical removal is essential, and radiation is used more often here than in other melanomas. Desmoplastic melanoma also tends to carry a very high number of gene mutations from sun exposure, which is thought to be one reason it can respond especially well to immunotherapy when it spreads.

How radiation treats it.

Radiation damages the DNA inside cancer cells so they can no longer divide and survive, while normal cells are better at repairing themselves. Most melanomas respond poorly to radiation, but desmoplastic melanoma is an important exception: radiation after surgery meaningfully lowers the chance of the cancer coming back, especially when the tumor was on the head and neck, had close margins, or grew along nerves. The radiation field is sometimes extended along an involved nerve's path to cover cells that surgery cannot see. It is given as short, painless daily sessions and leaves no radioactivity in your body, so you remain safe to be around family and children.

The ways we can treat it.

Surgery. Wide local excision with clear margins is the primary treatment; on the face, specialized techniques help remove the tumor completely while preserving as much healthy tissue as possible.

Adjuvant radiation. External-beam radiation to the tumor bed after surgery reduces local recurrence, which matters more here because of the tumor's nerve-tracking growth and frequent head-and-neck location.

Radiation along nerve pathways. When the tumor has invaded nerves, the radiation field can be extended along the involved nerve's path to cover microscopic disease that surgery may not reach.

Questions we hear often.

Why didn't my melanoma look dark? Desmoplastic melanoma often makes little or no pigment, so instead of a dark spot it can look like a firm, flesh-colored or pink lump or a scar-like patch on sun-damaged skin. That is one reason it is easy to miss and is often found later than other melanomas.

Why am I being offered radiation when melanoma usually isn't treated that way? Desmoplastic melanoma is an exception. It tends to grow along nerves and often sits on the head and neck, so radiation after surgery is frequently used to lower the chance it comes back in the same area — even though radiation is not a routine part of treating most other melanomas.

Do I need a lymph-node biopsy? It depends on the type. The 'pure' form rarely spreads to lymph nodes, so a sentinel-node biopsy is often not needed. The 'mixed' form behaves more like ordinary melanoma, so node sampling is usually considered. Your team will base this on your pathology.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.