by Glenda Wright MD and Allison Osmond MD FRCPC
November 2, 2022
A Spitz nevus is a non-cancerous skin tumour and a type of mole. Like other types of moles, these tumours are made up of specialized cells called melanocytes that are normally found in a part of the skin called the epidermis. The nevus is named after Dr. Sophie Spitz, a pathologist who first described them.
Spitz nevi tend to grow quickly at first, forming pink or brown coloured bumps on the surface of the skin. They typically do not cause any pain.
These nevi are typically found on the head, neck, or legs of children and young adults.
At present we do not know what causes this type of nevus to form.
No. A Spitz nevus is a non-cancerous growth.
No. The tumour cells are only found in the skin. They cannot spread to other parts of the body.
Most Spitz nevi are diagnosed after the entire tumour has been removed and sent to a pathologist for examination under the microscope. If the tumour shows any unusual features, the tissue may be sent to a pathologist who specializes in diagnosing skin lesions, called a dermatopathologist, to give a final diagnosis.
Spitz nevi are made up of melanocytes that are found in the epidermis, dermis, or both. In the epidermis, melanocytes in the tumour form groups called nests. The nests are often separated from each other and from the epidermis by open spaces called clefts.
As the nevus grows, melanocytes eventually enter the dermis. At the top of the dermis, melanocytes can be seen in nests, single cells, or both. As melanocytes go deeper into the dermis, the melanocytes get smaller in size. This process is called maturation. Maturation is an important feature that pathologists look for when examining a Spitz nevus under a microscope.
Two types of melanocytes can be found in a Spitz nevus – epithelioid melanocytes and spindle cell melanocytes. Epithelioid melanocytes are larger and have a rounder shape than normal melanocytes. In contrast, spindle cell melanocytes are long thin cells. It is normal to find one or both types of melanocytes in a Spitz nevus.
Round pink structures called Kamino bodies are often seen in a Spitz nevus. Kamino bodies are found in the epidermis and can be a helpful clue under the microscope in recognizing a Spitz nevus.
Junctional means that all of the melanocytes in the Spitz nevus were found in the epidermis on the surface of the skin.
Compound means that the melanocytes in the Spitz nevus were found in both the epidermis on the surface of the skin and in the dermis below.
Dermal or intradermal means that all of the melanocytes in the Spitz nevus were found in a layer of the skin just below the surface called the dermis.
Incompletely excised means that only part of the tumour was removed from the body. Pathologists describe a tumour as being incompletely excised when tumour cells are seen at the edge of the tissue. In pathology, the cut edge of the tissue is also called the margin. It is normal for a tumour to be incompletely excised after a small procedure such as a biopsy because these procedures are usually not performed to remove the entire tumour. However, larger procedures such as excisions and resections are usually performed to remove the entire tumour. If a tumour is incompletely excised, your doctor may recommend another procedure to remove the rest of the tumour.