1 2 3 4 4 5 6 7 8 Pigmented Skin Lesions MELANOMA MELANOMA Malignant melanoma is a skin cancer due to uncontrolled growth of pigment cells melanocytes. Melanocytes • Normal melanocytes occur in the basal layer of the epidermis • They produce melanin • Melanin (a protein) protects the skin by absorbing ultraviolet (UV) radiation • Melanocytes are found in equal numbers in black and in white skin • Melanocytes in black skin produce much more melanin • Non-cancerous growth of melanocytes results in moles (benign melanocytic naevi) and freckles • Cancerous growth of melanocytes results in melanoma Risk Factors for Melanoma • • • • • Sun exposure, particularly during childhood Fair skin that burns easily Blistering sunburn, especially when young Previous melanoma Previous non-melanoma skin cancer (BCC, SCC) • Family history of melanoma • Large numbers of moles (esp if > 100) • Abnormal moles (atypical or dysplastic naevi) Epidemiology of Melanoma • • • • 3% of all cancers and 10% of skin cancers. Incidence 1:10,000 per annum Incidence is increasing in developed countries Incidence rises with age, rare in children, commonest in over 75s • 3rd commonest cancer in young people. • In UK 2002 - 1,640 deaths from malignant melanoma Over 65% of deaths from malignant melanoma were in the over 65s. • It is commoner in women than in men but men have a worse prognosis. Melanoma in situ • Superficial forms of melanoma spread out within the epidermis (horizontal growth). • If all the melanoma cells are confined to the epidermis, it is melanoma in situ. • Lentigo maligna is a special case of melanoma in situ that occurs around hair follicles on the sun damaged skin of the face or neck. • Melanoma in situ is cured by excision Invasive Melanoma • When the cancerous cells have grown through the basement membrane into the deeper layer of the skin (the dermis), it is known as invasive melanoma (vertical growth) • Nodular melanoma appears to be invasive from the beginning, and has little or no relationship to sun exposure. • Metastatic disease increases in likelihood with increasing depth of the melanoma. • 15% of people with invasive melanoma will die from it. Where do melanomas occur? • Melanoma can arise from otherwise normal appearing skin (50%) • Or from within a mole or freckle, which starts to grow larger and change in appearance. Precursor lesions include: – Congenital melanocytic naevus (brown birthmark) – Atypical or dysplastic naevus (funny-looking mole) – Benign melanocytic naevus (normal mole) • Melanomas occur anywhere on the skin, not only in sun-exposed areas. Commonest sites: men - back (40%), women - leg (40%). • Melanomas can also occur on mucous membranes (lips, genitals). • May also occurs in other parts of the body such as the eye, brain, mouth or vagina. Moles (Melanocytic Naevi) • • • • Very common May be flat or protruding Vary in colour from pink to black Brown or black coloured moles are also called ‘pigmented naevi’. • Mostly round or oval in shape • Range in size from 2mm to several cm Moles • Most frequently moles arise during childhood or early adult life (acquired melanocytic naevi). • Exposure to sunlight increases the number of moles. • Teenagers and young adults tend to have the greatest number of moles. Classification • Junctional naevi Groups or nests of naevus cells at the junction of the epidermis and dermis. Tend to be flat colourful moles. • Dermal/Intradermal naevi Nests of naevus cells in the dermis. These moles are thickened and often protrude from the skin surface (papillomatous naevi). • Compound naevi Nests of naevus cells at the epidermal-dermal junction as well as within the dermis. These moles have a central raised area surrounded by flat pigmentation. Junctional Naevus Congenital Melanocytic Naevus • Brown or black naevi • Present at birth or develop in the first year or so of life • Moles that look like birthmarks but were not present at birth may be called ‘congenital naevus-like’ naevi or ‘congenital-type’ naevi. • About one baby in 100 has a small or medium sized congenital naevus, so they are quite common. • Very large, giant or bathing trunk naevi are very rare. Types of congenital melanocytic naevus • Typically multi-shaded, oval, fairly uniform pigmented patches • Most grow with the child but become proportionally smaller and less obvious with time. • May darken, become bumpy or hairy especially at puberty. • Rarely fade away or disappear. • Congenital melanocytic naevi in adults are classed as ‘small’ (< 1.5cm di), ‘medium’ (>1.5 <10cm) or ‘large’ (>10cm) • ‘Giant’ congenital naevi are greater than 20cm in diameter. Often found on the buttocks (‘bathing trunk’ naevi) • Café-au-lait macule - a flat tan mark, usually oval (inherited). Multiple café-au-lait macules may be a sign of neurofibromatosis. • Speckled lentiginous naevus (naevus spilus) has dark spots scattered on a flat tan background. Risk of Melanoma • The risk of melanoma in a small or medium-sized congenital melanocytic naevus is very small (< 1%) • Melanoma never arises from café-au-lait macules • Melanoma is more likely in the giant naevi (~ 5% over a lifetime) especially in those that lie across the spine Congenital Melanocytic Naevus Café au lait Macule Giant Melanocytic Naevus Speckled Melanocytic Naevus Atypical Naevi • Melanocytic naevi with unusual features eg indistinct edge, larger size. • May resemble Malignant Melanomoa but are benign • Sometimes called dysplastic naevi, active junctional naevi, B-K moles and Clark's naevi. • May be familial or sporadic. • The inherited form is usually part of a syndrome Familial Atypical Mole and Melanoma (FAMM) syndrome (formerly dysplastic naevus syndrome). – One or more first-degree or second-degree relative with malignant melanoma – A large number of naevi (often more than 50) some of which are atypical naevi – Naevi that show certain histological features. Atypical Naevi Fair-skinned individuals with light coloured hair and freckles are most at risk of getting atypical naevi, especially if they have been frequently exposed to the sun or have a family history of atypical naevi. Atypical naevi may develop at any time but most develop during the first 15 years of life. Atypical Naevi • People with one to four atypical naevi have a slightly higher risk than the general population of developing malignant melanoma • People with FAMM syndrome are significantly more at risk of developing melanoma. • Atypical naevi are harmless (benign) and do not need to be removed. However, it is not always easy to tell whether a lesion is an atypical naevus or a melanoma, so if in doubt, it should be removed by excision biopsy. Atypical Naevus Atypical Naevus Glasgow 7-point Checklist • Major features – Change in size – Irregular shape – Irregular colour • Minor features – Diameter >7mm – Inflammation – Oozing – Change in sensation ABCDE of Melanoma A. B. C. D. E. Asymmetry Border - irregularity Colour - variation Diameter - over 6 mm Evolving - (enlarging, changing) Types of Melanoma • Flat patches (horizontal slow growth) – Superficial spreading melanoma (SSM) – Lentigo maligna melanoma (sun damaged skin of face, scalp and neck) – Acral lentiginous melanoma (on soles of feet, palms of hands or under the nails – the subungual melanoma) • Nodules (vertical rapid growth) – Nodular melanoma – Mucosal melanoma (arising on lips, eyelids, vulva, penis, anus) – Desmoplastic melanoma (fibrous tumour with a tendency to grow down nerves) • Combinations occur e.g. nodular melanoma arising within a superficial spreading melanoma. Typical Superficial Spreading Melanoma Superficial Spreading Melanoma with regression Amelanotic Melanoma Lentigo Maligna Lentigo Maligna Melanoma Lentigo Maligna • • • • • • Sun-exposed areas of the face and neck Elderly Slow growing Often quite large (>20mm). Pre-cancerous Conversion to a lentigo maligna melanoma occurs in ~ 5% of patients • Identifying lesions that require referral is not easy – but see ABCDE Nodular Melanoma in Lentigo Maligna Acral Lentiginous Melanoma Subungual Melanoma Amelanotic Subungual Melanoma Nodular Melanoma Nodular Melanoma Nodular Melanoma Diagnosis • Excision biopsy with a 2 to 3-mm margin • Breslow depth - thickness of the melanoma in mm • Clark's level - describe which layer of the skin has been breached. Clark’s level 1 refers to melanoma in situ. Invasive melanoma may reach Clark's level 2 (thin) to 5 (reaching the subcutaneous fat layer). • Systematic search for metastasis Prognosis Death is unlikely if a melanoma has a Breslow thickness of less than 1mm 50% dead within 5 years if >4mm