PAEA Surgery End Of Rotation (EOR) Practice Exam

Which type of melanoma is characterized by asymmetric, flat lesions greater than 6 mm?

1. Nodular melanoma

2. Superficial spreading melanoma

3. Acral lentiginous melanoma

4. Amelanotic melanoma

The correct answer is: Superficial spreading melanoma

Superficial spreading melanoma is often characterized by asymmetric, flat lesions that typically exceed 6 mm in diameter. This type of melanoma is the most common variant and tends to grow horizontally on the skin, giving it a flat appearance. Lesions may display irregular borders and a variety of colors, including tan, brown, black, red, or even white. The asymmetry noted in these lesions arises from the irregular distribution of pigment and variations in color, making it a key aspect for diagnosis. The flat nature is indicative of its horizontal growth, which is a hallmark feature of this melanoma subtype. Other types of melanoma, such as nodular melanoma, typically present as raised, and often dark, lesions rather than flat. Acral lentiginous melanoma is often found on the palms, soles, or under the nails, and while it can be flat, its common locations and clinical features differ from those of superficial spreading melanoma. Amelanotic melanoma tends to lack pigmentation altogether, making it less likely to present as a flat, pigmented lesion greater than 6 mm. Thus, the characteristics specific to superficial spreading melanoma make it the correct response to this question.