Scanning electron microscopy of disseminated superficial actinic porokeratosis.

A typical skin lesion from a patient with biopsy-confirmed disseminated superficial actinic porokeratosis (DSAP) was examined by scanning electron microscopy. The lesion was rimmed by a prominent but discontinuous cornoid lamella. The cornoid lamella was found to consist of a packed layer of keratinocytes whose orientation varied from parallel to the epidermis at the base of the lesion to perpendicular at the summit of the porokeratotic column. The central core of the cornoid lamella consisted of a tightly packed mass of keratin.