8770/0 Epithelioid and spindle cell nevus


Synonyms

Juvenile nevus
Juvenile melanoma
Spitz nevus


Definitions

Skin
ICD-O-3 topography code: C44

Spitz nevus is a benign proliferation of large spindled, oval or round melanocytes that arises in the epidermis and evolves into compound or intradermal stages. An initial period of rapid growth is followed by stabilization. The typical Spitz nevus presents as a pink to red, dome-shaped, sligthly scaly papule with even round borders. The lesions range in size from 1mm to >2cm. The anatomic distribution of Spitz nevi is wide; the most common locations are the face of children and thighs of young women. Most Spitz nevi are single lesions. In eruptive Spitz nevus, many papules may appear on a limb or even over the entire integument within a few weeks or months.
Spitz nevus begins as a proliferation of melanocytes at the dermal-epidermal junction. The melanocytes are separated by clefts from adjacent keratinocytes. As the lesion enlarges, the overlying epidermis thickens, and well circumscribed nests begin to form. With further enlargement, Kamino bodies may be observed in the epidermis. Compound Spitz nevus forms when junctional nests become incorporated into the dermis. Intradermal Spitz nevi are often associated with a slightly hyperplastic epidermis and thickened collagen bundles in the lower part of the lesion. An important characteristic of both compound and intradermal Spitz nevi is that the nests of melanocytes, as well as the cells themselves, are similar in size and pigmentation at each level of the lesion.
Spitz nevus most commonly arises in the first two decades of life. Spitz nevi generally do not recur after surgical removal1
 
LeBoit PE, Burg G, Weedon D, Sarasin A (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Skin Tumours
3rd Edition
IARC Press: Lyon 2005



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