Other physical examination findings, such as inflammation and crusting should be considered, and historical features such as a new, pruritic, bleeding, or changing nevus should also alert one to the possibility of melanoma. The major subtypes of melanoma include superficial spreading, nodular, lentigo maligna melanoma, and acral lentiginous melanoma. It can occur anywhere on the skin, but most frequently involves the trunk in men and lower extremities in women. The median age at diagnosis is 44. They generally arise from preexisting nevi and demonstrate asymmetry, pigment variegation, and irregular borders.
Nodular melanomas are the second most common form of melanoma.
As their name implies, they are usually nodular or polypoid. They may be evenly pigmented and have regular borders and be easily mistaken for a basal cell carcinoma, seborrheic keratosis, or a benign nevus. Unlike superficial spreading and nodular melanomas, this subtype is associated with high cumulative doses of ultraviolet light. They are frequently asymmetric, have pigment variegation and irregular borders. They usually involve the palms, soles, or subungual region.