Identification of growth hormone receptor in plexiform neurofibromas of patients with neurofibromatosis type 1

OBJECTIVE: The aim of this study was to investigate the presence of growth hormone receptor in plexiform neurofibromas of neurofibromatosis type 1 patients. INTRODUCTION: The development of multiple neurofibromas is one of the major features of neurofibromatosis type 1. Since neurofibromas commonly grow during periods of hormonal change, especially during puberty and pregnancy, it has been suggested that hormones may influence neurofibromatosis type 1 neurofibromas. A recent study showed that the majority of localized neurofibromas from neurofibromatosis type 1 patients have growth hormone receptor. METHODS: Growth hormone receptor expression was investigated in 5 plexiform neurofibromas using immunohistochemistry. RESULTS: Four of the 5 plexiform neurofibromas were immunopositive for growth hormone receptor. CONCLUSION: This study suggests that growth hormone may influence the development of plexiform neurofibromas in patients with neurofibromatosis type 1.

Expression of CyclinD1, p27kp-1, and bcl-2 in plexiform neurofibroma with and without malignant transformation in neurofibromatosis type 1.

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.