Pigmented skin lesions
What are pigmented skin lesions?
Pigmented skin lesions refer to lesions that are brown, black or blue in colour, or may be confused with brown or black lesions (eg vascular lesions, which sometimes look black with the naked eye but under dermatoscopy appear red, purple or blue).
What is the pigment?
The colour of pigmented skin lesions is due to:
- Exogenous pigment (eg tattoo)
What are the possible diagnoses for pigmented skin lesions?
Pigmented skin lesions are most often melanocytic. However, non-melanocytic lesions can also be pigmented, particularly in dark-skinned individuals. Non-melanocytic lesions are keratinocytic, vascular, or reactive.
- Seborrhoeic keratosis
- Lentigo (freckles of various kinds including solar lentigo)
- Epidermal naevus including Becker naevus
- Pigmented basal cell carcinoma
- Pigmented actinic keratosis and intraepidermal carcinoma (also called squamous cell carcinoma in situ, Bowen disease)
- Pigmented squamous intraepithelial lesions of vulva, penis, anus
- Pigmented invasive squamous cell carcinoma
Pigmented keratinocytic lesions
- Trauma eg splinter haemorrhage in nail
- Purpura from bruise, capillaritis, vasculitis
- Cherry angioma
- Kaposi sarcoma
- Dermatofibrosarcoma protuberans
- Postinflammatory pigmentation
- Other pigmented skin condition such as lichen planus
Many other lesions and skin conditions are occasionally mistaken for a melanocytic or keratinocytic pigmented skin lesion.