Features
A Combined naevus is defined as "a melanocytic naevus formed by combination of epidermally and dermally derived naevus cells".
Clinically, they are raised, variegated lesions, displaying sandy and blue/black pigmentation due to their dual origin in the skin. They may have irregular borders and tend to be between 2 and 7mm in diameter. They are easily confused with malignant melanoma.
Incidence
Very common
Aetiology
Overgrowth of melanocytic cells in both the epidermis and dermis of unknown aetiology.
Differential Diagnosis
Malignant melanoma. Atypical mole. Dermatofibroma. Seborrhoeic keratosis. Blue naevus.
Treatment
None required. However, if the lesion displays any suspicious signs (detailed in the section on malignant melanoma) excision biopsy with histological examination may be necessary to rule out the possibility of malignant melanoma.