Most melanocytic lesions are benign but are often confused with melanoma and excised 'needlessly'; unfortunately there are no exact rules with melanoma and it is often better to be scarred and safe than sorry.
Spitz Naevus
An uncommon benign junctional or compound melanocytic tumour of childhood that may mimic melanoma.
Epidemiology
The tumour is rare and occurs in the first two decades of life in most cases.
Aetiology
Unknown
Pathological Features
Macroscopically, the most common appearance is of an erythematous papule that may resemble a haemangioma. Some cases are pigmented.
Microscpically, there is a proliferation of epithelioid melanocytes at the junction between the epidermis and dermis, which usually form nests of cells. Advanced cases may spread into the dermis, again forming nests. Mitotic activity may be present. Kamino bodies (pink globules within the epidermis) may be present. Melanoma can be difficult to differentiate from a Spitz naevus, but may be suspected by virtue of anaplastic features, extension into the subcutis, or superficial ulceration.
Blue Naevus
A proliferation of melanocytes within the dermis; the normal overlying epidermis gives a characteristic 'blue' tinge. Microscopically, the tumour is formed by isolated melanocytes with abundant collagen. HMB45 staining is universal, unlike melanoma which is an important differential.
Dysplastic Naevus
Dysplastic naevus syndrome is characterised by the presence of multiple, atypical melanotic lesions. While the majority are benign, patients are at elevated risk for melanoma (5-20 times the incidence). Melanoma may arise de novo or within a dysplastic naevus. Regular observations of the skin are essential to detect changing lesions that require excision.
