Published online May 16, 2018. doi: 10.12998/wjcc.v6.i5.88
Peer-review started: January 15, 2018
First decision: February 28, 2018
Revised: March 4, 2018
Accepted: April 1, 2018
Article in press: April 1, 2018
Published online: May 16, 2018
A nineteen-year-old male presented with a slowly growing, painless, multinodular mass on the right ischioanal fossa.
Clinical diagnosis was a dilemma due to no characteristic clinical feature observed.
Magnetic resonance images and histopathologic examination were focused on to differentially diagnose plexiform schwannoma from multilocular or multinodular ancient schwannoma, liposarcoma, cavernous haemangioma and plexiform neurofibroma.
There was no specific laboratory testing contributing to the diagnosis of plexiform schwannoma.
Magnetic resonance images showed an intratumoral nonenhanced capsule dividing the tumour into multiple homogeneously enhanced nodules.
Neoplasm biopsy revealed Verocay bodies, fibrous capsules, and diffuse positivity for S100 and vimentin.
Complete resection combined with the Bascom advancement flap to suture a large defect was performed to prevent a recurrence.
Plexiform schwannoma commonly located on head, neck, trunk and extremities was definitely diagnosed based on postoperative histopathologic examination, whereas the foci located in the perianal region was rarer and was more difficult for preoperative diagnosis without a specific nerve of origin.
Perianal plexiform schwannoma is an extremely rare variant of schwannoma and is difficultly diagnosed in clinic owing to the absence of a specific nerve of origin and a characteristic clinical manifestation.
Due to a multinodular growth pattern, a suspectable plexiform schwannoma can be preoperatively confirmed according to the magnetic resonance imaging feature of an intratumoral nonenhanced capsule dividing the tumour into multiple homogeneously enhanced nodules, which contributes to plan treatment protocol.