In 1948 Leider1 reported a case of osteoma cutis secondary to acne and compared it with Hopkins'2 case, which was also secondary to acne of long duration. Ossifying processes in the skin are indeed rare occurrences, especially when there is no history of preexisting lesions, like nevi, epitheliomas, scars, chronic inflammatory dermatoses. Prior to 1928, Hopkins2 could find about five cases; since then eight more cases have been reported,* in only one of which was the disease reported as having been primary.
The case here reported is nearly an exact replica of Hopkins' case2 and Leider's1 case so far as the distribution on the face is concerned, except that the two cases mentioned above were secondary to acne while the case reported now is primary. The Table is a summary of the relevant and comparative data of the three cases. Moreover, comparison of the Figures