Pigmented actinic keratosis and porokeratosis

Actinic keratoses (AKs) are the most common lesions within the spectrum of keratinocyte skin cancer.1-6 They typically arise on chronically sun-damaged skin of fair skin-type individuals, presenting as pink to red macules, with variably scaly surfaces. Less frequently, AKs may present a clinically visible pigmentation, pigmented AK (PAK) (Figure 32.1). PAK can be difficult to differentiate from other pigmented lesions such as melanoma and lentigo maligna melanoma, solar lentigo, early seborrheic keratosis, and lichen planus-like keratosis. In the context of actinically damaged skin, characterized by the presence of mottled pigmentation, discriminating between benign macules and pigmented tumors may be challenging; thus, histopathologic confirmation is frequently required in the diagnosis of PAK in order to exclude melanoma.