A Spitz nevus is a type of rare, non-cancerous skin growth that typically impacts people under 35 years old.
Spitz nevus growths, or Spitz nevi, were once considered a type of skin cancer. They have since been shown to be benign, or non-cancerous, and relatively harmless.
Spitz nevi were also initially thought to only develop in children. Although 70 percent of cases develop in people under 20 years of age, they can appear in anyone of any age.
Spitz nevus tumors are often called Spitz moles or growths. There are several different types, and many Spitz moles change as they grow.
While they can develop anywhere on the body, most Spitz moles appear on the face, head, and lower legs.
Spitz moles tend to grow rapidly compared to other moles. They vary in width between a few millimeters to centimeters.
Classic Spitz moles are often dome-shaped and reddish-brown to pinkish, but they may also be colorless.
Often, spitz moles that are black, blue, or dark tan have an irregular border, and are called pigmented Spitz moles.
Pigmented Spitz moles are thought to account for around 10 percent of all classic Spitz nevi.
In most cases, Spitz nevi change as they grow, switching between classic and pigmented forms before eventually fading away.
A Spitz nevus often starts out light-colored and round and progresses into a pigmented Spitz mole.
Similarly, some pigmented Spitz moles become red, pink, skin-colored, or even translucent before slowly disappearing.
Other common characteristics of classic and some pigmented Spitz moles include:
- rapid growth, often to a width of less than 6 millimeters (mm) in under 6 months, followed by no growth
- clear margins
- uniform color
- isolated but rarely in clusters
- bleeding and oozing a clear discharge
- itching on or around the mole
- smooth surface
- prominent blood vessels resembling bright red dots, corkscrews, or hairpins
In a small number of cases, Spitz nevus growths resemble cancerous melanoma tumors. These are called atypical Spitz tumors (AST).
Common characteristics of atypical Spitz tumors include:
- larger than 1 centimeter (cm) in width
- unclear, poorly defined margins or borders
- irregular, variable color
- scaly, rough, or flaky appearance
- located on the back
- open wounds or cracks
Classic and pigmented Spitz nevi are considered harmless. Some Spitz nevi eventually disappear, usually leaving only a temporary area of discoloration.
However, some atypical Spitz tumors have been linked to melanoma. Researchers are not sure how the conditions relate.
Very few atypical Spitz tumors progress to melanoma and lead to serious health risks, especially when diagnosed and treated early. A suspicious Spitz nevus is usually removed by a doctor while it is still benign.
If an atypical Spitz tumor becomes cancerous, it is called a Spitzoid melanoma.
If doctors are not sure if a Spitz nevus is cancerous, but it displays the potential to be so, the lesion is called a Spitzoid tumor of uncertain malignant potential, or STUMP.
As with most growths, Spitz nevi develop because of the overproduction and buildup of cells, in this case, skin melanocytes.
Researchers are not sure why some people develop Spitz nevus growths, and others do not, or why some growths progress to become Spitzoid melanomas.
However, there are a few risk factors that may increase or influence the chances of developing Spitz nevi and Spitzoid melanomas.
Risk factors for Spitz nevi include:
- being fair skinned or prone to sunburn
- repeat history of sunburn or severe burns
- puberty, especially for females
- being under 10 years of age
- having light-colored hair
- having freckles
- having a lot of moles
Additional risk factors for atypical Spitz tumors and Spitzoid melanomas include:
- hormonal changes in girls and women
- being between 10 and 20 years of age
- family history of melanoma and skin cancer, especially familial atypical multiple mole–melanoma (FAMMM) syndrome
- genetic mutations, which occur in around 12 percent of atypical Spitz tumor cases
In most cases of Spitz nervus, dermatologists will ask questions about an individual and their family medical history.
A dermatologist will also examine the growth with a dermatoscope.
This is a handheld tool with a high-powered magnifying lens and light.
They may add attachments to the dermatoscope, such as a camera or video camera, to capture additional information.
Information gathered by the dermatoscope is usually analyzed by a computer and compared to data from other non-cancerous and cancerous growths.
For most adult cases, and instances where a dermatologist is still unsure whether a Spitz nevus is cancerous or not, they will remove the growth or a portion of it. This section will go to a lab for examination.
Some atypical Spitz tumors and pigmented Spitz nevi will also require a sentinel lymph node biopsy (SLNB) to test for a melanoma that has metastasized, or spread, to the lymph nodes.
Traditionally, Spitz nevi were always excised or surgically cut out of the skin. But, excision can cause scarring.
Today, in non-cancerous cases involving young children, doctors recommend medical monitoring, in the first instance.
In a 2013 survey, 45 percent of dermatologists and 96 percent of plastic surgeons said they would elect to remove the growth by excision or biopsy if given a case involving a 7-year-old with Spitz nevus.
In the same survey, 21 percent of dermatologists and 2 percent of plastic surgeons said they would choose to observe the Spitz nevus before deciding to remove it.
Individuals can also be told how to recognize the early warning signs of melanoma and to monitor the growth of their mole or moles at home.
For classic and pigmented Spitz nevi that are less than 1 cm in width, symmetrical, and involve individuals 12 years of age and younger, a doctor will examine them every 6 months until the lesions have stopped changing and growing.
Spitz nevi will usually be removed if they:
- are pigmented
- occur in a person more than age 12 years
- are atypical in shape and color
- are STUMPs
Classic Spitz nevi usually grow for a few months and then gradually fade away over the course of a few years. They may only require medical monitoring.
Spitz nevi in adults and types that may be linked to melanoma, such as pigmented and atypical Spitz tumors, are usually surgically removed from the skin.
People should see a doctor for Spitz growths that:
- are more than 1 cm in width
- have ulcers or open wounds and cracks
- are growing rapidly
- cause anxiety or seem odd
- are asymmetrical
- are a mix of colors
- do not have clear borders
While most Spitz nevi are harmless, it is a good idea for people to have moles that look suspicious examined and monitored by a dermatologist.