Skeletal changes in epidermal nevus syndrome: does focal bone disease harbor clues concerning pathogenesis?
Epidermal nevus syndrome (ENS) is a rare, sporadic, congenital disorder of unknown etiology featuring a complex and highly variable phenotype that can include focal or generalized skeletal disease. We describe a young man with ENS manifesting right-sided linear skin lesions, generalized weakness, diffuse osteopenia associated with hypophosphatemic rickets, and distinctive focal bone lesions ipsilateral to the skin findings. Review of the literature concerning ENS-associated skeletal disease suggested such focal bone defects are fibrous dysplasia, but our patient did not have the typical radiographic or histopathologic findings of fibrous dysplasia. Nevertheless, his circulating fibroblast growth factor 23 (FGF-23) level was elevated, likely functioning as a "phosphatonin," yet no activating mutations in GNAS previously reported in fibrous dysplasia or McCune-Albright syndrome were detected in his leukocytes or affected skin. We postulate that the focal skeletal disease, although different than fibrous dysplasia, may be a source of FGF-23 in ENS.
Heike
Carrie L
CL
Department of Pediatrics, Children's Craniofacial Center, University of Washington and Children's Hospital and Regional Medical Center, Seattle, Washington 98105-5371, USA. cheike@u.washington.edu
Cunningham
Michael L
ML
Steiner
Robert D
RD
Wenkert
Deborah
D
Hornung
Robin L
RL
Gruss
Joseph S
JS
Gannon
Francis H
FH
McAlister
William H
WH
Mumm
Steven
S
Whyte
Michael P
MP
D000293:Adolescent; D000328:Adult; D001847:Bone Diseases / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D000089703:Fibroblast Growth Factor-23; D006801:Humans; D008297:Male; D009506:Nevus / Q000150:complications / Q000503:physiopathology*; D013577:Syndrome; D014057:Tomography, X-Ray Computed