Low-level mesodermal somatic mutation mosaicism: late-onset craniofacial and cervical spinal hyperostoses.

[proteus syndrome]

Craniofacial and cervical spinal hyperostoses are rarely seen in the absence of other abnormalities . Only seven patients with isolated cranial hyperostoses have been reported , and only a single patient with both calvarial and cervical vertebral hyperostoses . We report on an adult with late-onset right -sided asymmetrical hyperostoses of the cranium , mandible , and cervical vertebrae in the absence of an AKT 1 mutation . At presentation , the patient displayed neither generalized overgrowth nor dysregulated adipose tissue . Standard polymerase chain reaction and Sanger sequencing of DNA extracted from formalin-fixed paraffin-embedded frontal bone and mandibular angular bone was negative for an AKT 1 mutation . Though the patient 's clinical manifestations did not fulfill the consensus diagnostic criteria of Proteus syndrome , the mosaic distribution of lesions , the sporadic occurrence , and the patient 's progressive course were consistent with a somatic mosaicism similar to that syndrome . Hence , the patient 's phenotype may have been caused by a very late mesodermal somatic mutation during embryogenesis .