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Skin lesions

Malignant melanoma key points test

Which of the following statements are correct? # The incidence of melanoma in New Zealand is around 4000 per 100,000 #! The lifetime risk in fair-skinned New Zealanders is estimated to be 1:25 # Melanoma is rare below the age of 40 # Ninety-five per cent of melanoma can be specifically attributed to sun exposure. Explanation: The incidence of melanoma in New Zealand is around 50 per 100,000 and the lifetime risk is estimated to be 1:25. Melanoma is rare in children below the age of 12. Two-thirds of melanoma can be specifically attributed to sun exposure. Risk factors for melanoma include: #! Large numbers of melanocytic naevi # Large café-au-lait macule #! Blistering sunburn in childhood # Childhood spent in Scotland Explanation: Those with large numbers of melanocytic naevi and fair skinned individuals who have had repeated sunburns are at increased risk of melanoma. Although melanoma may arise in congenital melanocytic naevi, they are very rare within café au lait macules. They are much more common in those whose childhood was spent in Australia and New Zealand than in those whose childhood was spent in Northern Europe. Characteristics of melanoma include: # Change in size and colour over a few days # Steel-blue uniform colour #! Irregularity of outline and surface # Pearly rolled edge Explanation: Characteristics of melanoma include change in size and colour over a few months, irregularity of colour within the lesion, and irregularity of outline and surface. A pearly rolled edge describes a basal cell carcinoma rather than melanoma. Match the name of the lesion with its description: Mix and match: Superficial spreading melanoma: Horizontal growth Nodular melanoma: Dome-shaped Acral lentiginous melanoma: Palms and soles Lentigo maligna: Enlarging facial freckle Which of the following statements are correct? # A punch biopsy is the best way to diagnose a 7mm diameter suspicious pigmented lesion #! Primary excision of a pigmented lesion should include a 2mm margin # Benign melanocytic naevi removed for cosmetic reasons do not require histological examination # A skin graft is required after excision of 70% of melanomas Explanation: Biopsy of pigmented lesions on the basis of suspicious clinical features requires complete excision with a 2mm margin and pathological examination. All surgically removed melanocytic lesions should be evaluated histologically. Ten-year survival rates for melanoma are approximately: # 99% for those that are >0.75mm thick # 40% for those that are >1.5mm <3.0mm thick #! 55% for those that are >3.0mm <4.0mm thick # 10% if it is >4.0mm thick at the time of primary excision. Explanation: Ten-year survival rate for melanoma <0.75mm thick is 97.9% but only 40% if it is >4.0mm thick at the time of primary excision.