Congenital defect of the skin in the newborn is a comparatively rare occurrence. Not more than 125 cases have been reported. And of these it is interesting to note that the great majority were cases of lesions of the scalp. Thus in 1930 Terruhn's1 review showed 76 cases in which the head was involved and 29 in which the rest of the body was involved. Since then there have been few reported cases.
Greig2 described two forms of local congenital defects of the hairy scalp not involving the bone: one appearing as a bulla or raw surface and the other entirely membranous or cicatricial. The usual appearance is that of a deep, circular ulcer of varying size, either single or multiple, most common over the vertex of the skull but likely in any location. The lesion may be more extensive, as in Dowler's3 case of a normal
ROGATZ JL, DAVIDSON HB. CONGENITAL DEFECT OF THE SKIN IN A NEWBORN INFANT. Am J Dis Child. 1943;65(6):916-919. doi:10.1001/archpedi.1943.02010180092013