Porokeratosis of Mibelli
Porokeratosis of Mibelli is a distinctive quasi-benign neoplasm of the skin that is characterized by a raised ridge that surrounds the abnormal keratinocytic process. It comes in several variants, including palmoplantar keratoderma, Disseminated Superficial Actinic Porokeratosis, Porokeratosis of Mibelli, linear porokeratosis, and punctate porokeratosis. This case is Porokeratosis of Mibelli (PM), the largest of the porokeratoses. Occasionally, they can transform into SCC or BCC.
Clinically, PM is distinguished by its size, which is usually > 1 cm, its solitary nature and its oval shape. I've seen them over 5 cm wide, but those are really rare. Often, if examined closely, it has the dual wall (like the Great Wall of China) somewhere around the cornoid lamella. In this case, the dual wall is most prominent around the nine o'clock border.
I gave credit if you called this porokeratosis, PM or DSAP.