Perineurioma



Perineurioma


Thomas Mentzel, MD









Perineurioma is composed of spindled tumor cells containing uniform fusiform nuclei and thin, elongated cell processes image. In addition, plump tumor cells with round nuclei are seen image.






Immunohistochemical staining for perineural markers (e.g., claudin-1) highlights the presence of thin and elongated cell processes in neoplastic perineural cells.


TERMINOLOGY


Synonyms



  • Intraneural perineurioma (localized hypertrophic neuropathy of the limbs)


  • Extraneural perineurioma (storiform perineural fibroma)


  • Sclerosing perineurioma


Definitions



  • Benign mesenchymal neoplasm composed of neoplastic perineural cells


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Very rare neoplasms


  • Age



    • Intraneural perineuriomas occur in adolescents and in early adulthood


    • Extraneural perineuriomas occur in adults of all ages


    • Children are only rarely affected


  • Gender



    • Intraneural perineurioma shows no sex predilection


    • Extraneural perineurioma shows slight female predominance


Site



  • Intraneural perineurioma is seen in peripheral nerves of limbs


  • Extraneural perineurioma arises most frequently on trunk and extremities


  • Sclerosing perineurioma tends to occur in superficial tissue of hands


Natural History



  • Progressive muscle weakness &/or sensory disturbances are seen in intraneural perineurioma


  • Extraneural perineurioma is not associated with neurofibromatosis


Treatment



  • Surgical approaches



    • Resection of affected nerves should be avoided as long as possible in intraneural perineurioma


    • Complete excision is advised in extraneural perineurioma


Prognosis



  • Intraneural perineuriomas are benign mesenchymal neoplasms


  • Malignant peripheral nerve sheath tumors with perineural differentiation (malignant perineuriomas) are extremely rare


MACROSCOPIC FEATURES


General Features



  • Intraneural perineurioma



    • Characterized by fusiform swelling of affected nerves


    • Segmental enlargement of affected nerve


  • Extraneural perineurioma



    • Solitary, well-circumscribed, unencapsulated, nodular neoplasms


    • Frequently in subcutaneous tissue, whereas deep soft tissue and dermis are more rarely affected


  • Sclerosing perineurioma



    • Arises more frequently in superficial dermal location


MICROSCOPIC PATHOLOGY


Histologic Features



  • Intraneural perineurioma



    • Residual S100 protein(+) nerve fibers are surrounded by EMA(+) perineural tumor cells



    • EMA(+) perineural cells form concentric layers around nerve fibers with characteristic pseudo-onion bulbs


  • Extraneural spindle cell perineurioma



    • Variable cellularity


    • Different growth patterns (storiform, lamellar, fascicular)


    • Spindled tumor cells with elongated spindled nuclei


    • Round, slightly enlarged tumor cells


    • Collagenous stroma may show focal hyalinization


    • Presence of focal infiltration and cytologic atypia does not affect benign biologic behavior


    • Rare hybrid forms of perineurioma/schwannoma and perineurioma/neurofibroma have been reported


  • Sclerosing perineurioma



    • Composed of plump spindled and epithelioid tumor cells


    • Hyalinized stroma containing numerous thin-walled blood vessels


    • Perivascular and lace-like arrangement of neoplastic cells often seen


    • Neoplasms showing combination of extraneural spindle cell and sclerosing perineurioma have been reported


  • Reticular perineurioma



    • Prominent degenerative myxoid &/or edematous stromal changes


    • Pseudocystic spaces may be present


    • Tumor cells with thin and elongated cell processes anastomose in lace-like, reticular pattern


    • Occasionally degenerative cytologic atypia is noted


  • Plexiform perineurioma



    • Extremely rare morphologic variant


    • Plexiform architecture of neoplastic perineural cells


  • Sclerosing pacinian-like perineurioma, lipomatous perineurioma, ossifying perineurioma, and perineurioma with granular cells represent very rare morphologic variants

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Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Perineurioma
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