Amitabh Srivastava, MD

The cut surface of neurofibroma is pale, homogeneous, waxy, and often myxoid in appearance. Degenerative changes typically seen in schwannomas are seldom present in neurofibroma.

Histologic examination shows the classic hypocellular appearance of spindle and wavy cells with angulated or ovoid nuclei and thin cell processes amid a loose myxoid matrix image.



  • Neurofibroma (NF)


  • von Recklinghausen disease = neurofibromatosis type 1 (NF1)


  • Benign peripheral nerve sheath tumor composed of Schwann cells, fibroblasts, perineurial-like cells, and residual nerves in myxoid/collagen matrix



  • Neurofibromas are sporadic in about 90% of cases; others are syndromic in association with NF1

    • NF1 results from germline mutation in NF1 gene on chromosome 17q11.2

      • NF1 gene encodes for neurofibromin protein, which is a GTPase-activating protein

      • Neurofibromin also acts as a tumor suppressor by downregulating the Ras signal transduction pathway

    • Sporadic tumors arise from somatic mutations in NF1

  • Evidence supporting neoplastic nature of NF

    • Sporadic tumors are histologically similar to NF1-associated neurofibromas

    • Tumors are monoclonal on X chromosome inactivation studies

    • Lesional cells carry NF1 gene deletion



  • Incidence

    • Most common tumor of peripheral nerve

    • NF1 incidence: 1 in 2,500-4,000 births

  • Age

    • Solitary, sporadic lesions: In patients 20-30 years old

    • Tumors in setting of NF1 present during puberty

    • Plexiform NF may be congenital

  • Gender

    • Affects both sexes equally


  • Most tumors are solitary and sporadic

  • Superficial cutaneous or localized intraneural NF present as painless, palpable mass

  • Deep intraneural tumors may present with pain or dysesthesia

  • Intraspinal (nerve root) NF may show signs of spinal cord compression

Natural History

  • Slow-growing tumors in most instances

    • Increased rates of growth may be seen in puberty and pregnancy

  • Malignant transformation in NF

    • Rare in sporadic tumors; usually occurs in setting of NF1

    • Very rare in cutaneous NF (0.001%)

    • More common in plexiform NF (2-10%)

    • Clinical suspicion for malignant transformation

      • Rapid enlargement of preexisting NF

      • Pain or change in neurological symptoms


  • Surgical approaches

    • Complete resection is curative

    • Decompression of spinal cord in symptomatic tumors

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Neurofibroma

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