Fig. 7.

Unlike neurofibromas, schwannomas are composed almost exclusively of neoplastic Schwann cells and their supporting vasculature. (a) Hematoxylin and eosin stained section of an acoustic schwannoma resected from a 27 year old Caucasian man with NF2. (b, c) Acoustic schwannoma immunostained for the Schwann cell markers S100β (b) and collagen type IV (c). Note that immunoreactivity for the basement membrane protein collagen type IV invests each individual tumor cell. (d) Double label immunohistochemical preparation of an acoustic schwannoma stained for S100β (green) and CD34 (orange-red). In this tumor, unlike the neurofibroma illustrated in Fig. 1, CD34 immunoreactivity is only evident in intratumoral blood vessels.