case_images: PMC6767708_01
case_images: Intraoperative view of the right-forearm schwannoma. Full enucleation of
  the schwannoma from the median nerve was readily achieved: the
  nerve/tumor complex was isolated from the surrounding structures (a), a
  well-defined cleavage plane was demonstrated and the tumor was
  meticulously dissected from the nerve fascicles (b), and then completely
  removed (c). The nodule was a  3 cm beige ball weighing  7 g.
case_images: 10.1177_1756287219875578-fig1.jpg
case_images: PMC6767708_01_10.1177_1756287219875578-fig1.jpg
case_images: fig1-1756287219875578
case_images: Although painless, this median-nerve schwannoma was large enough ( 3 cm) to soon become a medical problem, and was thus readily resected without significant neural damage (Figure 1).
case_images: Microscopic characterization of the right-forearm schwannoma. (a) HES
  stain, x100 magnification. (b) S100 protein immunostaining, x100
  magnification.. HES, Hematoxylin-eosin-safran.
case_images: 10.1177_1756287219875578-fig2.jpg
case_images: PMC6767708_01_10.1177_1756287219875578-fig2.jpg
case_images: fig2-1756287219875578
case_images: As shown in Figure 2a, the excised tumor consisted in spindle-shaped cells with poorly defined eosinophilic cytoplasm, without atypia, and with nuclear palisading. In addition, strong and uniform immunoreaction for S100 protein (polyclonal, Ventana, prediluted) was seen in all tumor cells (Figure 2b).
case_images: Preoperative MRI evaluation (a,b) and intraoperative view (c,d) of the
  left-knee nodule. Two well-circumscribed lesions involving the common
  fibular nerve and the tibial nerve, respectively, were identified (a,b).
  While they both exhibited an heterogenous T2 hypersignal, they showed a
  weak and strong gadolinium-mediated enhancement (not shown),
  respectively. The common fibular nerve schwannoma was larger
  (24 x 14 mm) than the tibial nerve one (15 x 9 mm) and was readily
  enucleated without any neural damage (c,d). The common fibular nerve was
  carefully handled and its upper part with its lateral sural cutaneous
  branch was surgery free (c).. MRI, magnetic resonance imaging.
case_images: 10.1177_1756287219875578-fig3.jpg
case_images: PMC6767708_02_10.1177_1756287219875578-fig3.jpg
case_images: fig3-1756287219875578
case_images: The second left-knee nodule is the third schwannoma identified so far (Figure 3a,b), thereby indicating that, even though it has not yet been resected and formally characterized, we are facing an age-related schwannomatosis or neurofibromatosis type 2 (NF2) case.
case_images: Microscopic characterization of the larger left-knee schwannoma (common
  fibular nerve nodule). (a) HES stain, x50 magnification. (b) S100
  protein immunostaining, x100 magnification.. HES, Hematoxylin-eosin-safran.
case_images: 10.1177_1756287219875578-fig4.jpg
case_images: PMC6767708_01_10.1177_1756287219875578-fig4.jpg
case_images: fig4-1756287219875578
case_images: However, consistent with the MRI diagnosis, histologic and immunohistochemistry features were shown to be schwannoma-specific (Figure 4). Hematoxylin-eosin-safran (HES) stain disclosed alternating Antoni A and Antoni B patterns, hyalinized and thickened blood vessels, and cystic degenerative areas (Figure 4a). In addition, as in the aforementioned forearm nodule, strong and uniform immunoreaction was seen in all tumor cells for S100 protein (Figure 4b) but was absent for PSA (not shown).
case_images: PMC6767708_02
case_images: Preoperative MRI evaluation (a,b) and intraoperative view (c,d) of the
  left-knee nodule. Two well-circumscribed lesions involving the common
  fibular nerve and the tibial nerve, respectively, were identified (a,b).
  While they both exhibited an heterogenous T2 hypersignal, they showed a
  weak and strong gadolinium-mediated enhancement (not shown),
  respectively. The common fibular nerve schwannoma was larger
  (24 x 14 mm) than the tibial nerve one (15 x 9 mm) and was readily
  enucleated without any neural damage (c,d). The common fibular nerve was
  carefully handled and its upper part with its lateral sural cutaneous
  branch was surgery free (c).. MRI, magnetic resonance imaging.
case_images: 10.1177_1756287219875578-fig3.jpg
case_images: PMC6767708_02_10.1177_1756287219875578-fig3.jpg
case_images: fig3-1756287219875578
case_images: The second left-knee nodule is the third schwannoma identified so far (Figure 3a,b), thereby indicating that, even though it has not yet been resected and formally characterized, we are facing an age-related schwannomatosis or neurofibromatosis type 2 (NF2) case.