[Spreading pigmented actinic keratosis]

Two cases of spreading pigmented actinic keratosis are reported. In case number one, an invasive, pigmented squamous cell carcinoma developed in the lesion. Clinicopathologic features include size greater than normal, lateral spread of the lesion, and presence of melanin in dysplastic epidermal cells, dendritic melanocytes and dermal melanophages. Differential diagnosis to be considered includes lentigo maligna, lentigo maligna melanoma and seborrheic keratosis.