During a routine physical examination, the nurse observes a 7 mm (0.3 inch) lesion on an older adult client's head. The lesion is a brown-to-black macule with color variation and irregular borders. Which type of skin cancer does the nurse suspect?

Choice A reason: Actinic keratosis is a precancerous lesion caused by sun exposure. It typically appears as rough, scaly patches, not as a pigmented macule with irregular borders. Choice B reason: Malignant melanoma is characterized by pigmented lesions with color variation, irregular borders, and asymmetry. The description of a brown-to-black macule with irregular borders strongly suggests melanoma, which is the most dangerous form of skin cancer. Choice C reason: Squamous cell carcinoma usually presents as a firm, red nodule or scaly lesion, not a pigmented macule. It does not typically have the irregular color variation described. Choice D reason: Basal cell carcinoma often appears as pearly or waxy nodules, sometimes with visible blood vessels. It is not typically pigmented with irregular borders.