Doctors must be experienced to be able to correctly diagnose and treat (or, more commonly, not treat) nevi and they have to make such decisions must cope with daily decisions regarding removal, biopsy, observation, or simple reassurance.
The number of moles among individuals varies greatly. An increased number is seen in those with light-coloured skin and hair, those with more sun exposure or sunburns, and those with a family history of large numbers of moles. More moles are seen in those with leukaemia, chemotherapy, and immunosuppression for organ transplantation. The average number of moles ranges from 3-5 in preschool years to 20-30 in adolescence. Peak number is reached in the third decade of life, with a slow waning after the age of 40 years.
Many acquired moles will traverse a life cycle of early junctional nevi (flat, light brown/black macules) to compound nevi (slightly raised with smooth or warty surface) to intradermal nevi (dome-shaped or pedunculated fleshy papules), although there is little to be gained by making this clinical distinction.
In general, they will have good symmetry, sharp borders, uniform brown colour, diameter of 6 mm or less, and will not be rapidly enlarging or changing (ABCDE rule – asymmetry, border, colour, diameter, and evolution) which distinguishes them from atypical nevi or malignant melanoma. Diagnosis is usually simple.
Treatment is needed only in rare cases, although cosmetic concerns or intermittent trauma from rubbing may prompt removal. Shave excision after local anaesthesia is simple and usually leaves a very acceptable result. Common-sense judgment is needed in the evaluation for malignant melanoma. Since the incidence of melanoma is about one in a million in pre-pubertal children, clinicians need not panic over minor atypical features, opting instead to follow lesions with serial exams and photography. The possibility for melanoma becomes more believable in teenage years but remains very rare so a slightly to moderately unusual mole might be followed clinically whereas the same mole might be removed more quickly in an adult. Any mole removed for any reason must be sent for pathologic review. A complete excision must be done in those removed for the possibility for melanoma.
A few variants of melanocytic nevi deserve special mention. A blue nevus is a macule or papule with deep blue/black colour that can be congenital or acquired. It looks much like a graphite pencil tattoo but can also have a very ominous appearance. Its static nature is reassuring and simple observation is most often appropriate. If it is to be removed, it must be done by deep punch or elliptical excision since a shave will not approach the deep margin
Halo nevi may be seen alone or in conjunction with vitiligo. A rim of hypo- or depigmentation is seen surrounding a pigmented macule or papule. Many halo nevi may be seen in the same patient. They are felt to represent an immunologic response to a melanocytic nevus, and the nevus will slowly resorb over the course of many years with return of the normal skin pigmentation. Regression within a melanoma must be considered in adults with this finding but halo nevi are considered a common, benign entity in childhood.
Scalp nevi tend to have a characteristic ring of hyperpigmentation at their periphery and have been referred to as “eclipse nevi”. Their larger size and the doughnut-like irregularity of the pigment tend to raise concerns among parents who may be noticing the mole for the first time after a haircut. The pathologist may interpret their histology as atypical, which can add to the confusion. They are harmless and are best left alone.
The Spitz nevus may be the most confusing of all the variants, as illustrated by its somewhat oxymoronic synonym of benign juvenile melanoma. The typical Spitz nevus is an innocuous-appearing, red, sharply demarcated, dome-shaped, 5-10-mm papule. Some are easily mistaken as pyogenic granulomas. Another variety of Spitz nevus has a deeply pigmented, mottled or spiculated appearance that is much more ominous in appearance and more difficult to differentiate from a malignant melanoma. When recognized clinically, they can be left alone and followed. If removed, an experienced dermatopathologist will correctly recognize the lesion as a Spitz nevus, especially in the setting of a young child, but these lesions may be mistaken histologically for malignant melanoma, prompting unnecessary concern and surgical intervention. Whenever possible, any residual lesion should be completely excised to prevent future confusion and misdiagnosis should it recur at a later time.
Atypical nevi (dysplastic nevi) are another area of considerable confusion. They tend to cluster on the trunk, especially the back, but can be found in any location. Clinically they fulfil some or all of the ABCDE criteria used to assess the possibility of malignant melanoma of asymmetry, border irregularity, colour variation, diameter bigger than a pencil eraser (> 6 mm), and enlargement or evolution. As such, they need to be removed if the possibility of melanoma is suspected. There are histologic criteria that must be met to be classified as an atypical nevus and the cellular atypia will be graded by the pathologist as mild, moderate, or severe. Sometimes a definite distinction from melanoma cannot be made and the clinician will need to treat the lesion as though it were a melanoma.
Clinicians struggle with what to do with a confirmed diagnosis of an atypical nevus and wonder how to explain this entity to families. At one polar end of the spectrum there is the individual studded with atypical moles and s/he also has a strong family history of melanoma and atypical nevi. This is a patient at extraordinarily great risk, perhaps inevitability, of developing a melanoma. At the other pole is a patient with just one unusual mole with no family history of melanoma or atypical moles who probably has very little risk above the general population. There are countless shades of gray in between. A few points are fairly clear. An atypical mole should be completely removed because interpretation of a recurrence will be clinically and histologically difficult. At least one thorough, complete head-to-toe examination should be done and, depending on the stratification of risk factors, may be repeated on an annual basis with photographs to document the evolution of lesions. Patients must be taught self-examination skills, and very strict sun avoidance must become a lifelong practice. It should be made clear to patients that they have had neither a close brush with death nor a completely harmless lesion and that diligence without panic is required.
About 1% of infants have congenital nevi that are present at birth or develop within the first several months of life. Most are small, less than 1.5 cm, or moderate, less than 20 cm, in size. The rules of symmetry, colour, and shape are broken by almost all small and medium congenital nevi but they behave in a very harmless fashion and are cut some slack with the usual “good mole/bad mole” criteria. There may be a slightly elevated risk of malignant degeneration in adulthood compared to regular acquired nevi, perhaps simply commensurate with the increased number of melanocytes within them. Prophylactic excision to eliminate this small risk is not recommended, although some congenital nevi cause significant cosmetic disfigurement and warrant removal.
Large congenital (> 20 cm) nevi occur in 1 in 20 000 newborns, with giant congenital nevi often > 50 cm (bathing-trunk nevi) occurring far less commonly than that. These moles have substantial pigment irregularity, verrucous, convoluted surfaces, and hypertrichosis. Nodularity and ulceration may be present. These are dangerous lesions that carry significant malignant potential and, unlike small congenital nevi, may degenerate into melanomas in the first several years of life. The risk of malignant degeneration is hotly contested but probably is about 6%, with a wide margin of error. Large lesions are often associated with smaller satellite lesions that have little risk of developing melanoma. The central nervous system may be involved – a condition called neurocutaneous melanosis. This is most common when the nevus covers the scalp, neck, or spine. It may never have any associated complications but might lead to seizures, neurologic deterioration, and central nervous system melanoma, all of which portend a very bad prognosis.
Treatment of large and giant congenital nevi is difficult at best. It is desirable to remove as much of the mole as possible but doing so without devastating scarring and poor cosmetic outcome can be difficult. Even with excision, melanoma may occur in the deep tissues or in the central nervous system so a 100% reduction of melanoma risk is impossible. Families should be referred to an experienced plastic surgeon, carefully counselled in the proven (albeit fuzzy) risks of melanoma, and then allowed to make a personal decision that they feel is best for their baby. Ongoing lifelong follow-up is necessary.
Malignant melanoma is thankfully very uncommon in the paediatric age group outside the setting of large congenital nevi. It is at least a possibility among mid to upper teen age groups. Light skin and hair, previous sun exposure and sunburns, large number of moles, presence of dysplastic moles, and family history of melanoma in a first-degree relative are all risk factors for developing melanoma. Melanomas follow the ABCDE rules that were mentioned for dysplastic nevi. Actually it may be difficult clinically to specify the difference between a dysplastic nevus and a melanoma. It may develop on normal skin or within a pre-existing nevus. A biopsy specimen must be completely around and underneath the mole since prognosis and treatment are based on depth and invasiveness. The best is to use an elliptical or saucerised excision. After diagnosis, it is necessary to perform a wider re-excision and decide whether it is appropriate to perform sentinal lymph node analysis.
Mole mapping is the best method for timely diagnosis of skin cancers.
Mole (nevi) mapping is the most advanced method for the timely diagnosis of skin cancer. Through the use of a medical camera high-quality photographs are collected (digital dermoscopy). Moreover, the overall photographing of the body allows the mapping of the moles so they are easily and accurately located during the follow-up examinations.
During regular re-examination the initial and follow-up photographs can be compared, which allows the detection of even the slightest differentiations and possible occurrence of skin cancer at an early stage.
Each and every differentiation should be examined immediately and assessed!
- Colour changes (e.g. fading or intensity of colour, new colourations)
- Size changes – increase or decrease
- Changes of the surrounding skin (e.g. redness, white spots, oedema)
- Itching, sore, strange feeling
- Newly emerging nevi