case_images: PMC5830161_01
case_images: A 59-year-old woman presented with a 1-month history of numbness on the plantar surface of her left foot. Discomfort occasionally radiated proximally along the medial aspect of the calf. She had a traumatic history of hitting the bottom of her foot on a sharp rock. On physical examination, obvious wasting of the left abductor halluces and foot intrinsic muscles was seen (arrow).
case_images: 10-1055-s-0038-1632405-i1700052cr-1.jpg
case_images: PMC5830161_01_10-1055-s-0038-1632405-i1700052cr-1.jpg
case_images: FI1700052cr-1
case_images: On physical examination, obvious wasting of the abductor halluces and foot intrinsic muscles on the left foot was visible ( Fig. 1 ).
case_images: Plexiform neurofibroma. Multiple hypoechoic round masses surrounded by a hyperechoic background. The diameter of each mass measured 0.5 to 0.8 cm. (
  A
  ) Short-axis ultrasound (US) image obtained over the calcaneus shows plexiform neurofibroma as a fusiform solid hypoechoic mass (arrow). (
  B
  ) Long-axis US image obtained over the calcaneus shows plexiform neurofibroma as a cordlike hypoechoic mass (arrow). (
  C
  ) T1-weighted image shows a multiloculated tubular lesion within the tarsal tunnel (arrow). (
  D
  ) T1-weighted image shows a cordlike mass lesion below the calcaneus (arrow). (
  E
  ,
  F
  ) T2-weighted image shows a multiloculated tubulocystic lesion along the tibial nerve, lateral plantar nerve, proximal medial plantar nerve, and posterior calcaneal nerve, from the distal tibial plafond level to the fifth metatarsal base level.
case_images: 10-1055-s-0038-1632405-i1700052cr-2.jpg
case_images: PMC5830161_01_10-1055-s-0038-1632405-i1700052cr-2.jpg
case_images: FI1700052cr-2
case_images: We also identified fusiform swelling of the nerve, which was indicative of tumor origin from a neurofibroma ( Fig. 2A , B ). Fig. 2C , D ) and high-signal intensity on T2-weighted images ( Fig. 2E , F ). Findings on physical examination and imaging were consistent with a diagnosis of a PNF of the foot. 
case_images: A multiloculated plexiform mass originated from the posterior tibial nerve (
  A
  ). Plexiform arrangement (x10, hematoxylin and eosin [H&E] stain) (
  B
  ) composed of wavy spindle cells (x400, H&E stain) (
  C
  ) on histopathological examination.
case_images: 10-1055-s-0038-1632405-i1700052cr-3.jpg
case_images: PMC5830161_01_10-1055-s-0038-1632405-i1700052cr-3.jpg
case_images: FI1700052cr-3
case_images: The mass originated from the posterior tibial nerve and involved the calcaneal branch, medial plantar nerve, and lateral plantar nerve ( Fig. 3A ).  Histopathological examination of the excised mass confirmed the diagnosis of PNF ( Fig. 3B , C ).