The concept that tumor-like keratoses of Poth,1 primary self-healing squamous-cell epithelioma of the skin,2 and keratoacanthoma3 are variants of the same disease is steadily gaining ground.4 Rapid development, benignity, and spontaneous involution with scarring and typical pathology are common to all three types of tumors. There are, however, a number of divergent elements in the three entities which have to be elucidated upon before this unicist theory can be recognized as final.
On the other hand, familial incidence is present only in the primary self-healing squamous-cell epithelioma of the skin. The multiplicity of lesions, their recurrence, or a chronic clinical course are witnessed in the tumor-like keratoses of Poth and in the primary self-healing squamous-cell epithelioma of the skin. The face is the usual site for keratoacanthoma, which develops as a single lesion, grows to the largest size, and occurs in