Congenital pseudarthrosis of the tibia, which is recalcitrant to treatments and prone to recur, is frequently associated with neurofibromatosis. The causative gene for neurofibromatosis, NF1, has been identified, but the pathomechanism of congenital pseudarthrosis has not been elucidated. The purposes of this study were to establish primary cell culture from the fibrous hamartoma tissue of pseudoarthrosis, and to compare the gene expression patterns of the fibrous hamartoma and normal bone.

Incubation of the enzymatically treated fibrous hamartoma tissue resulted in growth of the adherent fibroblast-like spindle cells. Expression of hundreds of genes including bone morphogenetic protein-2 and -4, and NF1 were screened by reverse transcription-polymerase chain reaction and cDNA array hydridization methods.

Bone morphogenetic protein-2 and -4, and, NF1 were found to express in normal bone, normal periosteum as well as fibrous hamartoma and adjacent hypotrophic bone. Twenty-four genes were found to express exclusively in the fibrous hamartoma, and fifty genes only in the normal bone.

These findings suggest that the causative gene of neurofibromatosis, NF1, may be associated with pathogenesis of the congenital pseudoarthrosis of the tibia in neurofibromatosis patients.