Skin, pigmented lesions

Probability diagnosis

Naevi: congenital and acquired

Seborrhoeic keratoses

Solar keratoses

Freckles

Lentigines

Serious disorders not to be missed

Pigmented squamous cell carcinoma

Pigmented basal cell carcinoma

Melanoma:

• lentigo maligna

• superficial spreading melanoma

• nodular melanoma

• acral lentiginous melanoma

Other disorders

Haemangioma (thrombosed)

Dermatofibroma

Pyogenic granuloma

Foreign body granuloma

Talon noir (black heel)

Becker naevus

Common melanocytic naevi:

• congenital

• acquired

  • — junctional → compound → intradermal

  • — halo

  • — blue

  • — spitz

  • — dysplastic melanocyte

Key history

Establish the history of the lesion and associated features. Family history, especially of melanoma. Determine history of past residential (geographic) areas, sun exposure, history of sunburn and the practice of preventive measures.

Key examination

• Systematic examination of the skin especially searching for melanoma

• Starting at the head, examine the hairline, backs of the ears, neck, back and backs of the arms. Pull down the underwear to expose the buttocks, examine the backs of the legs and feet. Then examine the front of the body including the anterior surfaces of the legs

• Apply the ABCDE system to a suspicious lesion: Asymmetry, Border, Colour, Diameter, Evolution and/or Elevation

Key investigations

• Photography to monitor dysplastic naevi

• Dermoscopy

• Excision biopsy

Diagnostic tips

• Most pigmented lesions are benign but one-third of all melanomas arise in pre-existing naevi, many of which are dysplastic.

• Melanoma is extremely rare before puberty.