Melanoma

Melanoma, also called malignant melanoma or cutaneous melanoma, is a malignant neoplasm (cancer) arising from uncontrolled growth of melanocytes, the pigment producing cells of the skin and are derived from the neural crest.

It usually arises in the skin and accounts for only 5% of skin cancers, but 75% of skin cancer death (Boring 1994). The incidence of melanoma has sharply increased in the last 70 years, with present lifetime risk corresponding to 1 in 74 persons compared to 1 in 1500 in the 1930s (Rigel 2000). Melanoma can develop in either a pre-existing pigmented lesion or de novo (from new) in previously normal looking skin (>50% arise de novo) Features raising suspicion of melanoma in a pre-existing pigmented lesion include: - change in size, - irregular shape, - irregular colour, - diameter 6-7 mm or more, - inflammation, - oozing, - itching, - and change in sensation (MacKie 1989; MacKie 1990) Late signs - ulceration, - bleeding Risk Factors-Multifactorials Race: …celtic -Blue eyes, fair skin, freckling, red hair -Incidence: African 1/12th , Hispanic 1/6th vs white Sex: -Slight female predilection Age: -Peak incidence 4th decade -Commonest Ca in young adults (20-39yrs)

Sun exposure (UVB): -Short, intense episodes, blistering -Severe sunburns <10yrs age (4X more frequent) Family history: -5-10% patients -one affected relative, 2.2X higher risk Previous melanoma: -3-5% risk of a 2nd primary MM Congenital giant hairy naevus: -Lesions >20cm in adult or cover >5% TBSA -Life-time risk malignancy 2-4% (40% reported) Dysplastic naevus: -Irregular border, patchy pigmentation, >5mm -Atypical naevus syndrome = >100 naevi -12X risk of MM

] ] ] } only ~10% MM arise in ]pre-existing naevus ] ] ] ]

Fitzpatrick skin type

Skin type classification

Features

Do you burn in the sun?

Do you tan after having been in the sun?

I

Extremely fair skin

Always

Seldom

II

Fair skin

Usually

Sometimes

III

Medium skin

Sometimes

Usually

IV

Olive skin

Seldom

Always

V

Moderately pigmented brown skin

Never

Always

VI

Markedly pigmented

Never

Always

black skin (Thomas B. Fitzpatrick, MD, PhD, of Harvard Medical School,1975) - People with pale or freckled skin, fair or red hair and blue eyes belong to the highest risk group (skin types I, II); - People with dark hair and eyes who do not normally get sun burnt are at medium risk of developing skin cancer (skin types III, IV) - Naturally brown and black people (skin types V, VI – see table) can usually safely tolerate relatively high levels of sun exposure without getting sun burnt or greatly increasing their skin cancer risk Major Malignant Melanoma Subtypes  Superficial spreading melanoma –most common

 Nodular melanoma  Lentigo maligna melanoma  Acral lentiginous … most melanoma -characterised by a radial growth phase prior to vertical growth but nodular MM ~ concurrent radial & vertical phase Rare Melanoma variants (<2%)  Desmoplastic  Mostly Head & neck  High local recurrence, Low nodal mets (Lens 2005)  Amelanotic  Non-cutaneous  mucosal, ocular etc  Secondary MM (no identifiable primary)  Presents as lymph node disease , primary undergone regression

Suspicious lesions should be excised completely and sent for confirmatory histopathological examination (Roberts 2002; Sober 2001). In situations where complete removal is not practical (for example large site, difficult location), an initial incisional biopsy of the lesion should be considered. Avoid biopsy that transects the depth of the lesion (e.g. superficial shave biopsy) because histological depth of invasion is the basic criterion for staging. Prognosis Prognosis is affected by clinical and histological factors and by anatomic location of the lesion. Thickness and/or level of invasion of the melanoma, mitotic index, presence of tumor infiltrating lymphocytes, number of regional lymph nodes involved, and ulceration or bleeding at the primary site affect the prognosis.[3-6] Microscopic satellites in stage I melanoma may be a poor prognostic histologic factor, but this is controversial.[7] Patients who are younger, female, and who have melanomas on the extremities generally have a better prognosis.[3-6]

Staging Clark’s level Breslow’s thickness TNM Clinical staging Pathological staging

References Boring 1994 Boring CC, Squires TS, Tong T, Montgomery S. Cancer statistics, 1994. CA: a cancer journal for clinicians 1994;44(1):7–26. Rigel 2000 Rigel DS, Carucci JA. Malignant melanoma: prevention, early detection, and treatment in the 21st century. CA: A Cancer Journal for Clinicians 2000;50(4):215–40. MacKie 1989 MacKieRM.Malignantmelanoma. A guide to early diagnosis. University Department of Dermatology, 1989. MacKie 1990 MacKie RM. Clinical recognition of early invasive melanoma. British Medical Journal 1990;301:1005–6. Lens 2005 M.B. Lens; J.A. Newton-Bishop; A.P. Boon .Desmoplastic Malignant Melanoma: A Systematic Review.Br J Dermatol. 2005;152(4):673-678.