ABSTRACT
Plexiform neurofibroma (PNF) has a low potential to undergo malignant transformation. Identification of markers associated with tumor progression is important since it may serve as prognostic indicators or adjuncts to standard pathological examination. In the present study, the authors immunostained 20 neurofibromatosis type I-associated PNFs with cyclinD1, p27kip-1, and bcl-2. Six of the cases had progressed into malignant peripheral nerve sheath tumor (MPNST), and the transitional area of each sample was also stained separately in order to identify protein(s) associated with tumor progression. Cyclin D1 was found to be significantly increased in the transitional zone, compared to the ordinary PNF (p = 0.007). The protein is, thus, likely to play a role in the malignant transformation. There was no significant difference in the expression of p27kip-1 and bcl-2 during the malignant progression of PNF.