Keratosis punctata palmaris et plantaris. A morphological study on the relation to the epidermal sweat duct unit.

The palmar and plantar pits of keratosis punctata palmaris et plantaris were examined histologically in both vertical and horizontal sections. Pits were located in the crista superficialis epidermis, especially in the orifice of the sweat duct, but no iodine-starch reaction was detected in pits by perspiration testing. In the center of a pit was a parakeratotic wedge, deflecting the squamous cell layers downwards. The sweat duct was found in this parakeratotic wedge, and was occasionally obstructed.