Section Editor: Allison Osmond MD FRCPC
June 14, 2026
A Spitz nevus is a noncancerous (benign) skin growth and a type of mole. Like other moles, it is made up of cells called melanocytes, the cells in the skin that make melanin, the pigment that gives skin its color. The growth is named after Dr. Sophie Spitz, the pathologist who first described it. Spitz nevi are most common in children and young adults, and they often grow quickly at first, which can be alarming, even though the growth itself is harmless.
One reason Spitz nevi are important is that, under the microscope, they can look like melanoma (a serious skin cancer). For this reason, they are carefully examined, often by a specialist, and usually removed completely. This article explains what a Spitz nevus is, what the findings in your (or your child’s) pathology report mean, and why these growths are handled with care.
What causes a Spitz nevus?
Spitz nevi are caused by specific genetic changes in melanocytes that cause the cells to grow into a mole. Unlike most common moles, these changes are usually not a BRAF mutation and are not closely linked to sun exposure. Instead, a Spitz nevus most often carries either a change (mutation) in a gene called HRAS or a rearrangement (fusion) involving one of several genes, such as ALK, ROS1, NTRK1, NTRK3, RET, or MET. These changes happen by chance in the skin and are not inherited. Identifying which change is present can sometimes help the pathologist classify an unusual Spitz lesion.
What are the symptoms of a Spitz nevus?
A Spitz nevus usually appears as a firm, dome-shaped bump that is pink, red, or brown. It often grows quickly over a few weeks to months and then becomes stable. Spitz nevi are most commonly found on the head, neck, and legs of children and young adults and are usually painless. Because a new, quickly growing bump can be worrying, it is reasonable to have any such spot examined by a doctor.
How is the diagnosis made?
Most Spitz nevi are diagnosed after the entire growth has been removed and examined under the microscope by a pathologist. Because a Spitz nevus can closely resemble melanoma, the tissue is often reviewed by a dermatopathologist (a pathologist who specializes in skin diseases), and additional tests such as immunohistochemistry (special stains), FISH, or molecular testing may be used to help with difficult cases.
Under the microscope, a Spitz nevus is made up of two kinds of melanocytes: epithelioid melanocytes (larger, rounder cells) and spindle cell melanocytes (long, thin cells). It is normal to see one or both types. In the epidermis (the thin outer layer of the skin), the melanocytes form clusters called nests, which are often separated from one another and from the surrounding skin by clear spaces called clefts. As the cells extend downward into the dermis (the layer beneath the epidermis), they become smaller, a benign, orderly process called maturation. Round pink structures called Kamino bodies are often present and are a helpful clue that the growth is a Spitz nevus. The report may also describe where the melanocytes are located: junctional means they are found only in the epidermis; compound means they are found in both the epidermis and the dermis; and dermal (or intradermal) means they are found only in the dermis.
The Spitz spectrum: Spitz nevus, atypical Spitz tumor, and Spitz melanoma
Spitz growths are best understood as a spectrum, from completely benign to cancerous. Where a particular growth falls on this spectrum is the most important part of the diagnosis.
- Spitz nevus — A benign growth. It does not spread to other parts of the body, and once it has been completely removed, it typically does not come back. Most Spitz growths, especially in children, are in this group.
- Atypical Spitz tumor — A growth with some unusual features that fall between clearly benign and clearly cancerous, so the pathologist cannot be fully certain it is harmless. These are also called Spitz tumors of uncertain malignant potential. They are treated cautiously, usually with complete removal and sometimes additional testing or follow-up. Occasionally, a few cells are found in a nearby lymph node, but they usually do not behave like true melanoma.
- Spitz melanoma — A true melanoma with Spitz-like features. It can spread to other parts of the body and is treated as melanoma. This is the least common part of the spectrum.
Because these growths can look similar under the microscope, careful examination, expert review, and complete removal all help make sure a growth is correctly placed on this spectrum.
Surgical margins
A margin is the edge of the tissue removed during a procedure. For Spitz growths, the margin status is especially important because removing the entire growth allows the pathologist to examine it in full, which helps distinguish a benign Spitz nevus from an atypical Spitz tumor or melanoma.
- Negative margin — No tumor cells are seen at the cut edge, which means the growth was completely removed (sometimes described as “completely excised”).
- Positive margin — Tumor cells are present at the cut edge, which means part of the growth may remain (sometimes described as “incompletely excised”). This is common after a small biopsy meant only to make the diagnosis. When the goal is to remove the entire growth, a positive margin often requires a second procedure (an excision) to remove the remaining tissue.
What happens after this diagnosis?
For a typical, benign Spitz nevus that has been completely removed, no further treatment is usually needed. If the growth was only partially removed, your doctor may recommend a second procedure to remove the rest, both to treat the growth and to allow the whole thing to be examined. When a growth is classified as an atypical Spitz tumor, doctors often recommend complete removal with a wider margin of normal skin, and in some cases, referral to a specialist, additional molecular testing, or closer follow-up. A growth diagnosed as Spitz melanoma is treated as melanoma. In all cases, regular skin checks and sun protection are sensible parts of long-term care.
Questions to ask your doctor
- Was this a typical (benign) Spitz nevus, or did it have atypical features?
- Where does my growth fall on the Spitz spectrum?
- Was the whole growth removed, or were the margins positive?
- If the margins were positive, do I need another procedure?
- Was the tissue reviewed by a dermatopathologist?
- Were any special tests (immunohistochemistry, FISH, or molecular testing) done, and what did they show?
- Does my child or I need any further treatment or follow-up?
- How often should the area and the rest of the skin be checked?
- What changes should prompt me to call you?
- What can we do to protect the skin from sun damage?
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