Linear nevus sebaceous syndrome with hypophosphatemic rickets with elevated FGF-23.

BACKGROUND: Linear nevus sebaceous syndrome (LNSS) is a rare congenital neuroectodermal disorder characterized by involvement of the skeleton and central nervous system. CASE: We report the case of a 5-year-old girl who had LNSS with hypophosphatemic rickets and multiple fractures of her extremities. Biochemical tests revealed a high serum level of fibroblast growth factor-23 (FGF-23) but normal levels of immunoglobulin E (IgE) and parathormone (PTH). FGF-23 mRNA expression in the skin lesions of our patient's skin was found to be below the limit of detection in all samples tested by quantitative-PCR analysis.
CONCLUSIONS: It is possible that an as-yet unidentified substance increases FGF-23 expression LNS lesions.