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INTRODUCTION

The skin calls for the faculty of close observation and attention to detail.

LOUIS A DUHRING (1845–1913), VALEDICTORY ADDRESS, UNIVERSITY OF PENNSYLVANIA MEDICAL SCHOOL

The management of pigmented skin lesions is a constant concern for all practitioners and requires careful evaluation based on the natural history of these lesions and the increasing incidence of malignant melanoma in particular.

Most pigmented lesions are benign and include simple moles or melanocytic naevi, seborrhoeic keratoses, freckles and lentigines. Reassurance is all that is necessary in the management of these problems.

However, one-third of all melanomas arise in pre-existing naevi, many of which are dysplastic, and it is the recognition and removal of such naevi that is so important in the prevention of melanoma.1

Malignant melanoma is doubling in incidence each decade, which is an alarming statistic considering the public education programs about the hazards of sun exposure. Of equal interest is the fact that the cure rate for melanoma is also increasing, reflecting earlier diagnosis and treatment. The most important factor in management is early detection. It is most appropriate for GPs to acquire skills in dermoscopy, which significantly improves diagnostic accuracy for melanoma.2

A classification of pigmented skin lesions is given in TABLE 125.1.

Table 125.1Classification of pigmented skin lesions

Key facts and checkpoints

  • The incidence of melanoma is greatest in white Caucasians and increases with proximity to the equator.

  • The early diagnosis and treatment of melanoma profoundly affects the prognosis.

  • Melanoma is extremely rare before puberty.

  • Currently the greatest rate of increase is in men >55 years.

  • Most people have 5–10 melanocytic naevi on average.

  • Multiple dysplastic naevi carry a higher risk of malignant change, which may occur in young adults. Such patients require regular observation (with photography).

Pyogenic granuloma

Synonyms: granuloma, granuloma telangiectaticum, acquired haemangioma.

A pyogenic granuloma is a 5–10 mm soft vascular lesion (without pus) due to a proliferation of capillary vessels. It is considered to be an abnormal reaction to minor trauma (see FIG. 125.1).

FIGURE 125.1

Pyogenic granuloma showing bright red, friable tumour on face. It followed a puncture from a spiky plant in the garden.

Photo courtesy Robin Marks

Clinical features

  • Common in children and young adults

  • Usually on hands and face

  • Bright red ‘raspberry’-like lesion

  • Raised, sometimes pedunculated

  • Friable—bleeds easily

Beware of misdiagnosing pyogenic granuloma for a nodular melanoma.

Management

It must be distinguished from amelanotic melanoma or anaplastic SCC. Shave biopsy or curettage with electrocautery of base. The specimen must be sent for histological examination. They are prone to recur.

Talon noir (‘black heel’)

Talon noir is a black spotted appearance on the heel and is common in sportspeople. A similar lesion (probably smaller) is often found on the other heel.

‘Black heel’ is formed by small petechiae caused by the trauma of the sharp turns required in sport: shearing stress on the skin of the heel produces superficial bleeding. The diagnosis can be confirmed by gentle paring of the callus to reveal the multiple small petechial spots in the epidermis; these are then pared away. If there is doubt about the diagnosis (malignant melanoma is the main differential diagnosis), the lesion should be excised.

Tinea nigra

Tinea nigra is characterised by solitary black macular lesions on the palm or sole. The simple technique of taking skin scrapings to reveal fungal elements will allow easy differentiation from malignant melanoma.

Becker naevus

Becker naevus is a faint, brown, diffuse pigmented area with a component of coarse hairs and is usually found on the shoulder and upper trunk. It occurs mainly in boys around puberty. It is not a birthmark, it is benign and reassurance is appropriate.

Freckles

Freckles are small, brown flat macules (usually <0.5 cm), coloured by excessive epidermal melanin without any increase in the number of naevus cells (melanocytes). They occur mainly on light-coloured skin and tend to darken in summer and fade in winter. Cosmetic improvement can be achieved through the use of sunscreens.

Lentigines

Lentigines are small, rounded, brown to black macular areas ranging from 1 mm to 1 cm or more across. They are very common and may appear in childhood as a few scattered lesions, often on areas not exposed to the sun. In the elderly, lentigines often develop on sun-damaged skin, usually on the backs of the hands (so-called ‘liver spots’) and on the face.

Unlike freckles they have increased numbers of melanocytes.

Management

  • Treatment is usually unnecessary. Liquid nitrogen or excision can be used for cosmetically unacceptable lesions. Sunscreens are needed to prevent further darkening of existing lesions.

  • Otherwise, rather than use ‘fade cream’, use fresh lemon juice. Squeeze lemon juice (½ lemon) into a small bowl and apply the juice to the spots daily. Continue for 8 weeks.

  • Apply tretinoin 0.05% cream daily at night, if necessary.

  • Laser for severe cases.

Congenital melanocytic naevi

These moles are present at birth and are sometimes large.

Clinical features

  • Variable colour—brown to black

  • Sometimes hairy and protruding

  • Increased risk of malignant change (especially in larger ones)

Common acquired naevi

These are the common moles for which an opinion is so often sought. The moles are localised, benign proliferations of naevus cells. There may be a sharp increase in numbers during pregnancy. New lesions appear less frequently after the age of 20 years. The types are junctional, compound and intradermal. Naevi in children are usually the junctional type with proliferating naevus cells clumped at the dermo-epidermal junction. With time the naevus cells ‘move’ into the dermis. A compound naevus has both junctional and dermal elements. With maturation all the naevus cells move into the dermis. Refer to FIGURE 125.2.

FIGURE 125.2

Comparison of melanocyte (naevus cell) distribution in various common acquired naevi

Clinical features
Junctional

  • Usually <5 mm

  • Circular-shaped macules

  • May be slightly elevated

  • Colour usually brown to black

  • May be ‘fuzzy’ border

Most naevi of the palms, soles and genitals are junctional but there is no evidence to support the traditional view that naevi in these sites have more malignant potential.2

Compound

  • Dome-shaped, slightly raised pigmented nodules

  • Up to 1 cm in diameter

  • Colour varies from light to dark brown/black, but lighter than junctional naevi (see FIG. 125.3)

  • Most are smooth but surface can be rough or verrucoid

  • Larger ones may be hairy, especially after puberty

  • Become ‘flesh’-coloured in time

FIGURE 125.3

Compound naevus. This pigmented lesion, which was benign, has been present since birth. At puberty there is often a rapid increase in size and colour.

Photo courtesy Robin Marks

Intradermal

  • Look like compound but less pigmented

  • Often skin-coloured

  • May evolve to pink or brown senile nodules or to soft, pedunculated tags

Malignant potential of common acquired melanocytic naevi

  • Junctional: have significant potential to undergo malignant change (as long as junctional activity is present)

  • Compound: very rarely undergo malignant change

  • Intradermal: these are totally benign lesions

Management

  • Provide appropriate reassurance.

  • Observe.

  • If lesion is changing or there is uncertainty, perform surgical excision (2 mm margin) for histopathology.

Halo naevus

A halo naevus consists of a depigmented halo around a central melanocytic naevus (see FIG. 125.4). It is the result of an autoimmune reaction. The central naevus gradually involutes. It tends to occur around puberty. Multiple halo naevi are often seen on the trunk of adolescents.

FIGURE 125.4

Halo naevus in a child. The central lesion is usually a benign pigmented naevus.

Photo courtesy Robin Marks

Caution: A halo can occur around a melanoma.

Management

Measure the lesion. Reassure and do nothing, as it usually disappears over the next few years; if doubtful at all, remove and obtain histological diagnosis.

Blue naevus

A blue naevus presents as a solitary, slate-grey–blue dermal lesion. Blue naevi usually present in childhood and adolescence on the lower back and buttocks and the limbs, especially dorsa of the hands and feet. Malignant change is rare. They are often excised for cosmetic reasons.

Spitz naevus (benign juvenile melanoma)

Spitz naevi are also called benign juvenile melanomas or spindle cell naevi.

Clinical features

  • Solitary pigmented or erythematous nodules

  • Often appear in children, usually 4–8 years

  • Develop over 1–3 months

  • Well-circumscribed, dome-shaped lesions

Management

Surgical excision is treatment of choice (because of rapid growth and best ‘reassurance’ policy).

Dysplastic melanocytic naevi

These are large, irregular moles that appear predominantly on the trunk in young adults (see FIG. 125.5). They can be familial or sporadic and are markers of an increased risk of melanoma, rather than necessarily being premalignant lesions. Even so, melanoma may arise within these lesions more frequently than would be expected by random chance.3

FIGURE 125.5

Dysplastic melanocytic naevi. These lesions may have ill-defined borders and irregular pigmentation.

Photo courtesy Robin Marks

They are considered to be intermediate between benign naevi and melanoma.

Clinical features

  • Age: adolescence onwards

  • Large >5 mm (variable size)

  • Most common on trunk

  • Irregular and ill-defined border

  • Irregular pigmentation

  • Background redness

  • Variable colours—brown, tan, black, pink, red

  • Variation of colours within the naevus

  • Most are stable and do not progress to melanoma

Dysplastic naevus syndrome

The presence of multiple, large, irregular pigmented naevi, mainly on the trunk, presents a difficult management problem, especially if there is a family history of melanoma. The lifetime risk of melanoma may approach 100% for such patients.

Management

Use a follow-up program (similar to excised early melanoma) of 6 monthly review for 2 years (3-monthly if family history of melanoma) and yearly thereafter, provided no lesions become malignant during the first 2 years. During this time the patient and family should become well versed in surveillance. Apart from measurement, good professional-quality photographs of areas of the body including total body photography or specific lesions of concern may also be helpful.

Any suspicious lesions should be excised for histological examination.

Advice to patients

To decrease your chances of getting a melanoma, you should protect yourself from the sun. These rules should be followed.

  • Try to avoid direct sunlight when the sun is at its strongest (from 10 am to 3 pm).

  • Always wear a broad-brimmed hat and long-sleeved shirt in the sun.

  • Use an SPF 30 or more sunscreen on exposed skin and renew the sunscreen regularly.

  • Sunbaking might give you a good tan but it is also going to increase your chances of getting a melanoma, so you should avoid it.

Melanoma

Melanomas are malignant tumours derived from melanocytes, with the skin being the most common site.

The early diagnosis of melanoma is vital to outcome. Thickness of a melanoma when it is removed is the major factor determining prognosis: it is vital to detect melanomas when they are in the thin stage and look like an unusual freckle.

In Australia, only about 30% of melanomas develop in pre-existing melanocytic naevi (moles).2,3 The majority arise in apparently normal skin. Initially the tumour tends to spread laterally in many cases and it should be removed at this stage when it is easily cured. An irregular border or margin is suggestive of the tumour.

Risk factors

  • History of previous melanoma (fivefold)

  • Presence of many moles (50 or more), especially atypical dysplastic naevi

  • Family history (one or more members, especially first-degree relatives)

  • History of many sunburns

  • Sun sensitive skin/fair complexion

  • Patient age and sex: increasing age and male

  • Tanning (including solarium) treatments

  • History of multiple non-melanoma skin cancers

Clinical features

  • Typical age range 30–50 years (average 40 years)

  • Can occur anywhere on the body—more common: lower limbs in women, upper back in men

  • Often asymptomatic

  • Can bleed or itch

Warning signs

The sign of major importance is a recent change in a ‘freckle’ or mole:

  • change in size—at edge or thickening

  • change in shape

  • change in colour—brown, blue, black, red, violet, white, including combinations

  • change in surface

  • change in the border

  • bleeding or ulceration

  • other symptoms (e.g. itching)

  • development of satellite nodules

  • lymph node involvement

Red flag pointers for melanoma4

  • New or changing lesion (see preceding change list)

  • Rapidly growing nodule of any colour

  • Non-healing lump or ulcer

  • The ‘ugly duckling’ syndrome: a prominent pigment lesion that stands out from any other

  • A lesion that concerns the patient

  • Dermoscopic changes on follow-up or poor dermoscopic–clinical correlation

Types
Lentigo maligna3

Lentigo maligna (Hutchinson melanotic freckle) is a slow-growing form of intra-epidermal melanoma that occurs on areas exposed to light (usually the face), predominantly in older patients (see FIG. 125.6). If allowed to remain, it may become invasive and the prognosis will be similar to that for other invasive melanomas. These lesions have all the variations in size, shape and colour of superficial melanomas. Dermoscopic features include an annular-granular pattern, asymmetric follicular pigmented openings and rhomboidal structures.4 Lentigo maligna should be excised.

FIGURE 125.6

Lentigo maligna in a 72-year-old man. Excision is recommended as it is a form of intra-epidermal melanoma.

Photo courtesy Robin Marks

Superficial spreading melanoma

Like lentigo maligna, the initial growth is in a lateral or radial intra-epidermal manner, rather than in an invasive downward or vertical manner (see FIG. 125.7). It exhibits a striking colour variation. Through a dermatoscope there is typically a range of colours with architectural disorder, radial streaming, branched streaks, pseudopods, peripheral black dots and blue-white structures.4 It accounts for 70% of melanomas. It can be detected early by biopsy—shave is preferred to punch (less sampling error). Excisional biopsy is preferable.

FIGURE 125.7

Superficial spreading melanoma with an irregular border which has altered and variable colours. Requires excision.

Photo courtesy Robin Marks

Nodular melanoma

Nodular melanomas account for 20% of melanomas, are aggressive and invasive, and have no radial growth phase. They are typically found on the trunk and limbs of young to middle-aged individuals (see FIG. 125.8). It may have a ‘blueberry’-like nodule. Prognosis is determined by thickness at the time of excision. Dermatoscopy is usually less useful.

FIGURE 125.8

Nodular melanoma on the back. It has no radial growth phase and because it grows vertically can be readily misdiagnosed. The ABCD rule often does not apply but this lesion shows variable colours and an irregular border.

Photo courtesy Robin Marks

The early nodular melanoma problem4,5

Nodular melanoma can present a diagnostic dilemma since the ABCD rule (see later in this chapter) often does not apply. The mnemonic EFG, standing for ‘Elevated’, ‘Firm’ and ‘Growing for more than 1 month’, is more appropriate. Early melanomas tend to be symmetrical, non-pigmented, even in colour, of small diameter and to grow vertically.

They are often mistaken for a haemangioma or a pyogenic granuloma. If one is suspicious, refer early to a specialist/specialist clinic.

Acral lentiginous melanoma

These typically occur on palms, soles and distal phalanges (see FIG. 125.9). They have a poorer prognosis than other types. They occur mainly in people with dark skin.

FIGURE 125.9

Acral lentiginous melanoma. A 30-year-old man presented with a ‘mole’ on his toe that had become ‘lumpier’. This type of melanoma, which occurs on the distal areas of the limbs, begins as a spreading pigmented, macule before developing into a nodule surrounded by a pigmented halo (as shown).

Photo courtesy Robin Marks

Desmoplastic melanoma4

This is a rare and aggressive subtype of melanoma. They are often subtle clinically and sometimes scar-like. Most are non-pigmented.

Variations

Amelanotic melanomas are flesh-coloured papules that increase in size or change shape. These lesions can be extremely difficult to diagnose and the poor prognosis associated with them is due to late diagnosis rather than an increased malignancy.

The features and associations of melanoma subtypes are presented in TABLE 125.2.

Table 125.2Features and associations of melanoma subtypes5,6
Prognosis

Determinants of prognosis include:3

  • thickness (Breslow classification)

  • level or depth (worse in level IV or V) (see FIG. 125.10)

  • site (worse on head and neck, trunk)

  • sex (worse for men)

  • age (worse >50 years)

  • amelanotic melanoma

  • ulceration

FIGURE 125.10

Assessment of tumour level: the levels of melanoma invasion

Vertical growth is associated with invasion and the prognosis worsens with depth. The chance of cure is greater than 90% if a melanoma is removed when it is less than 0.75 mm thick.3 If the lesion is allowed to invade to a thickness of 4 mm or more, the likelihood of a cure is reduced to less than 30%.3

The influence of tumour thickness on 5-year survival rates is shown in TABLE 125.3.

Table 125.3The diagnostic model for a presenting problem

Staging is based on the tumour level (depth) shown in FIGURE 125.10:

  • level I—confined to the epidermis (in situ)

  • level II—tumour cells extend into the superficial (papillary) dermis

  • level III—tumour cells fill up the superficial dermis

  • level IV—tumour cells extend into the deeper (reticular) layer

  • level V—invasion of subcutaneous tissue

Differential diagnosis

There are several common skin lesions that may be mistaken for melanoma.1 They are:

  • haemangioma (thrombosed)

  • dermatofibroma (sclerosing haemangioma)

  • pigmented seborrhoeic keratosis

  • pigmented BCC

  • junctional and compound naevi

  • blue naevi

  • dysplastic naevi

  • lentigines

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