Cutaneous fibrous dysplasia: an incomplete form of the McCune-Albright syndrome.

A number of genetic disorders have been described in limited form. We report a patient with precocious puberty, large irregularly shaped café-au-lait spots since birth and a diffuse scalp alopecia showing the cutaneous changes of fibrous dysplasia. Histologically, the hair follicles were replaced by convolutions of fibrous tissue. This is to our knowledge the first patient reported with an apparently localized cutaneous form of this syndrome, a pattern predicted by the recently described somatic mutation of the Gs alpha gene. This is the second patient reported to our knowledge with the cutaneous McCune-Albright syndrome and scalp alopecia, and the first with diffuse scalp alopecia, the latter being the presenting sign. We believe that the differential diagnosis of both localized and diffuse alopecia should include the McCune-Albright syndrome.