Figure 1. Cutaneous neurofibromas, plexiform neurofibromas, and histology.

Example of cutaneous neurofibromas covering the chest and abdomen of a patient with neurofibromatosis type 1 (a). MRI of a large plexiform neurofibroma compressing the spinal column and abdominal viscera (b). Murine models of NF1-associated plexiform neurofibroma development develop enlarged dorsal root ganglia (c, red arrows), which are histologically comprised of wavy Schwann cells, numerous fibroblasts, and a granular mast cell infiltrate (d). Alcian blue deeply stains mast cell granules (e, red arrows), and trichrome stain highlights the abundant collagenization typical of neurofibromas (e). Human photograph samples reproduced with permission from the Children's Tumor Foundation: www.ctf.org.