Unilateral progressive osseous heteroplasia.

A 50-year-old male patient presented with firm subcutaneous nodules and plaques with a gritty texture, unilaterally affecting the left side of the trunk and the left limbs. These lesions had had a progressive course since early childhood and caused functional impairment. There was no family history of similar disorders. No phospho-calcium metabolism abnormalities were observed. Biopsies of the affected areas demonstrated osteoma cutis. Analysis of DNA showed no mutation of the GNAS gene. The clinical features were consistent with progressive osseous heteroplasia, atypically presented in a unilateral form, probably revealing a mosaic distribution.