Author: Vanessa Ngan, Staff Writer, 2003.
A Spitz naevus (or Spitz's nevus) is an uncommon type of mole (melanocytic naevus).
Spitz naevi are benign skin tumours. However, they may resemble malignant melanomas clinically and microscopically, so they are often excised as a precaution.
Spitz naevi are seen most often in children; 70% of cases diagnosed during the first 20 years of life. They may also arise in adults. They are most frequently found in fair-skinned individuals (skin phototypes 1 and 2) but can also affect those with dark skin.
A Spitz naevus is a type of melanocytic naevus, that is, it is a mole composed of melanocyes — these are cells that normally produce pigment, melanin, and are responsible for skin colour. The melanocytes in Spitz naevus may be inactive, thus the lesion may be pink rather than brown in colour. The genetic pattern of the DNA in Spitz naevus is characteristic.
It is not known why Spitz nevi occur.
A Spitz naevus is typically a dome-shaped red, reddish-brown papule. This is known as classic Spitz naevus. A darker papular or nodular type is called a pigmented Spitz naevus. The size ranges from a few millimetres to up to one or two centimetres in diameter. They usually appear on the face or limbs.
A Spitz naevus grows rapidly for a few months. After the initial growth period, if untreated, it may remain static for years. A Spitz naevus may disappear spontaneously after a period of time.
Spitz naevi are often suspected clinically by their characteristic dome-shaped appearance and rapid growth over a few weeks to months.
In older children and adults, the diagnosis of Spitz naevus is usually confirmed by skin biopsy. Histopathology usually shows a symmetrical compound naevus composed of nests of characteristic epithelioid cells.
In children under the age of 12 years, a Spitz naevus is often kept under review using digital dermatoscopic surveillance (monitoring photographs of the lesion's dermatoscopic appearance). It is expected to enlarge uniformly over a year or two and then to stop enlarging.
Because of the difficulty in definitively predicting the outcome of Spitz naevi in older children or adults, or if the structure of the lesion is not uniform, they are generally cut out (excised).
An atypical Spitzoid tumour or a Spitzoid tumour of uncertain malignant potential (STUMP) may be difficult to distinguish histologically from Spitzoid melanoma and is best widely excised. Sentinel node biopsy should not be undertaken as the results can be misleading.
If it hasn't been excised, a Spitz naevus may evolute (disappear) over a few years.
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