Dermoscopy, dermatoscopy, epiluminoscopy, epiluminescent microscopy (ELM) and skin surface microscopy describe the evaluation of pigmented skin lesions using magnification devices. Dermatologists use dermoscopy to examine pigmented lesions as an aid to the diagnosis of melanoma. Hand-held devices are most common (Dermatoscope®, Episcope®, Dermlite®). Oil-immersion or polarised lenses eliminate surface reflection so that epidermal and superficial dermal structures can be viewed.
There are characteristic features for many pigmented lesions allowing melanoma to be distinguished from seborrhoeic keratoses, pigmented basal cell carcinomas, haemangiomas, freckles and benign melanocytic naevi (moles). Considerable training and experience is required for reliable interpretation of dermoscopic images.
Digital images may conveniently be displayed on a computer using special lenses for still or video camera. Proprietary archiving software is available but specialist interpretation is necessary, as automated systems are not yet considered reliable. It is useful to be able to compare dermoscopic images of a melanocytic lesion taken at different times, as change may indicate malignancy.
Freckles (lentigines) are evenly pigmented brown macules.
|Ephelis||Common in redheaded children with fair skin. May fade or disappear in winter and with age.||
|Solar lentigo (1)||Scattered small brown lesions on sun-damaged areas||
|Solar lentigo (2)||Large well-defined oval patch on face in mature individuals|
Solar lentigines may appear similar to pigmented solar keratoses (adherent scale and tenderness) or flat seborrhoeic keratoses (dry surface).
The number of lentigines increases with age and can be reduced by careful sun protection.
Providing there is no chance that an individual lesion is a melanoma, the following may be helpful to fade freckles:
Results are variable but sometimes very impressive with minimal risk of scarring.
Resurfacing lasers (carbon dioxide and Erbium:YAG) that vaporise the surface skin, and cryotherapy, should not be used to remove pigmented lesions by non-specialists. Although they may improve the appearance of lentigines, they may instead result in unsightly patchy hypopigmentation or scarring.
Moles are melanocytic naevi, sometimes called naevocellular naevi. A few will appear in infancy, more in the second decade, and then a smaller number as an adult. Most people have about 20 to 50 moles. Sun exposure promotes a greater number of naevi. They often appear as light brown macules, become darker papules, and may eventually lose their pigmentation. Some include one or two terminal hairs. The number of moles reduces after the age of 50 – they disappear leaving no trace.
|Site of melanocytes (naevus cell nests)||Clinical image|
|Junctional naevus||Dermal-epidermal junction|
|Compound naevus||Dermal-epidermal junction and dermis|
|Dermal / intradermal naevus||Dermis|
|Blue naevus||Intradermal (heavily melanized)|
|Mongolian spot||Intradermal (melanized)|
Histology is shown below.
Congenital pigmented naevi may be small (1-5cm), medium (1.5-20cm) or rarely, giant (bathing trunk variety). The latter have a significantly increased risk of melanoma in the lesion (3%) or within melanocytes in the central nervous system hence surveillance should be lifelong.
Solitary café au lait macules are common but the presence of six or more is strongly suggestive of neurofibromatosis.
Halo naevi are common in teenagers. A white ring appears around a normal mole, which gradually fades and eventually disappears. Several years later the white mark may disappear. Histologically there is a lichenoid infiltrate.
Spitz naevi most often arise on the face of children and adolescents. They grow over a period of time, and are often red or black resembling melanoma. In adults, they are often excised to rule this out, and the pathologist may also find it difficult to distinguish the benign Spitz from a melanoma.
Atypical naevi are “funny-looking” moles. They may be more numerous, varied in colour (usually shades of brown), size (over 4mm diameter), shape, and contour (with an ill-defined border). Atypical naevi may predispose to melanoma, especially in patients with a strong family history of atypical naevi and melanoma (dysplastic naevus syndrome).
Most melanocytic lesions can be ignored, as they are harmless. Sun exposure increases the number and degree of atypicality of moles, a good reason for encouraging sun protection.
Moles may be removed for the following reasons:
Surgical removal may entail:
The coarse hair that sometimes grows in a mole can be removed by shaving. Plucking may cause inflammation resulting in a painful lump under the mole. The hair can only be removed permanently by electrolysis, laser epilation or excision of the whole mole.
Skin lesions that have been removed surgically should always be sent for pathology. If there is concern that a lesion could be a melanoma, it should be completely excised. If the lesion is too big for this to be practical or the scar will be unsightly, it is preferable to send the patient to a dermatologist for a specialist opinion.