This is a form of melanocytic naevus, but it appears to have the same degree of pigmentation as the surrounding skin. It is the classical skin-coloured 'mole', elevated from the skin's surface, that most people would recognise as such. The melanocytes do not impart their pigmentation to the lesion because they are located deep within the dermis, rather than at the dermo-epidermal junction (as is the case for junctional naevi / compound naevi).

They may appear spontaneously or grow from a pre-existing pigmented mole. They usually develop from the end of childhood onwards and may appear at any stage throughout adulthood, although they are probably quite rare as a new phenomenon after the age of 60. They have the following characteristics:

• Skin-coloured lesion (i.e. same degree of pigmentation as surrounding skin)
• Small (5mm–1cm)
• Raised from the surface of the skin (rounded, dome-shaped, pedunculated or warty appearance)
• May be associated with hair growth (particularly in older patients)

Visual appearance

Epidemiology

They are extremely common, as are all the melanocytic naevi. Indeed they affect so many people that some consider that they cannot be classed as a pathological entity, rather a normal variant.¹

Presentation

• They do not present that often as most people recognise them as a benign dermatological phenomenon.
• They may be detected coincidentally during a consultation, or brought up as a 'whilst I'm here' phenomenon.
• They are most likely to present if they are newly noticed.

Differential diagnosis

• Their history and appearance is fairly characteristic and so they are not usually confused with other lesions.
• They may resemble early basal cell carcinoma or a neurofibroma.
• Basal cell carcinoma will usually have a shorter history, be noted to be growing quite quickly and have associated telangiectasia.
• Where there is doubt as to the diagnosis then excision biopsy will resolve the question.

Investigations

• None usually required.
• If there has been significant recent growth then consider excision biopsy to exclude basal cell carcinoma.
• Where a previously non-pigmented lesion develops pigmentation then excision biopsy should be carried out.

Management

• No treatment is required unless the patient is concerned about the lesion's cosmetic appearance or there are suspicions of an alternative diagnosis.
• Excision biopsy may be used for diagnostic purposes.
• Shave and cautery (dermal electrosurgical shave excision) is a good method for removing them with apparently better cosmetic results than excision biopsy.
• Facial lesions may be best removed for cosmetic purposes by a dermatological surgeon or plastic surgeon, particularly in young patients, due to the high risk of medicolegal claims in this area of practice if there is a poor cosmetic outcome.

Complications

• Intradermal naevi have no complications as such and are benign, slow-growing lesions.
• If they occur in the external auditory meatus they can obstruct the auditory canal and impair hearing.²
• There are potential complications associated with their removal.

Prognosis

Excellent. A benign lesion with no risk of transformation to melanoma.