Benign and malignant nerve sheath tumors

Benign and malignant nerve sheath tumors
DR.N.PRIYADHARSHINI

1. BENIGN AND MALIGNANT NERVE SHEATH TUMORS Dr.Priyadharsini N Department of Oral Pathology and microbiology Srm dental college , ramapuram

2. Neurofibroma Common type of peripheral nerve neoplasm Arise from mixture of cells including perineural fibroblasts

3. Can arise as solitary tumor or neurofibromatosis Common in young adults Slow growing, soft painless lesion varying in size from small nodule to large masses

4. Skin is the most common location Tongue and buccal mucosa common in oral cavity Rarely arise within bone producing well demarcated or poorly define unilocular or multilocular radiolucency.

5. Histopathology Well circumscribed within perineurium When occurs outside tend to blend with adjacent connective tissues Composed of interlacing bundles of spindle shaped cells exhibiting wavy nuclei.

6. Associated with delicate collagen and variable myxoid matrix. Mast cells are numerous and are diagnostic Sparsely distributed small axons demonstrable by silver stains. IHC – S100 positive

7. Treatment Local surgical excision Recurrence is rare Should be evaluated for neurofibromatosis Malignant transformation possible.

8. Neurofibromatosis Common hereditary condition Eight forms have been recognized. Type I – von Recklinghausen disease Autosomal dominant trait Caused by NF1 gene mutation responsible for tumor suppressor protein neurofibromin

9. Clinical features Multiple neurofibromas that can occur anywhere in body Clinical appearance can vary from small papule to large soft nodules to massive baggy pendulous masses (elephantiasis neuromatosa ) on skin

10. Plexiform variant feels like a bag of worms and considered pathognomonic May be present at birth but appear during puberty Accelerated growth seen in pregnancy

11. Café au lait (coffee with milk ) pigmentation on skin Occur as yellow – tan to dark brown macules that vary in diameter from 1 – 2 mm to several centimeters. They have a smooth edge “coast of California” Coast of maine – Polyostotic fibrous dysplasia

12. Crowe sign – freckling of axilla

13. Lisch nodules – translucent brown pigmented spots on iris Hypertension, CNS tumors, short stature, scoliosis, mental deficiency are other complications

14. Oral manifestation Enlargement of fungiform papilla Only very few patient develop intraoral neurofibromas Radiograph shows enlargement of mandibular canal, increased bone density, concavity of medial surface of ramus

15. The 7 clinical criteria used to diagnose NF1 are as follows: (the patient should have two or more of following) Six or more café-au-lait spots or hyperpigmented macules greater than 5 mm in diameter in prepubertal children and greater than 15 mm postpubertal Axillary or inguinal freckles (>2)   Two or more typical neurofibromas or one plexiform neurofibroma Optic nerve glioma Two or more iris hamartomas ( Lisch nodules), often identified only through slit-lamp examination by an ophthalmologist Sphenoid dysplasia or typical long-bone abnormalities such as pseudarthrosis First-degree relative ( eg , mother, father, sister, brother) with NF1

16. Treatment Prevention and management of complications Facial neurofibromas can be removed using carbon di oxide laser and dermabrasion Some may require cosmetic remodeling surgery Complication – neurofibrosarcoma , MPNST

17. Shwannoma (Neurilemoma) Schwannoma is a benign neural neoplasm of Schwann cell origin. Relatively uncommon Schwannomatosis – multiple schwannomas Neurofibromatosis II – Bilateral schwannomas of auditory vestibular nerve

18. Clinical features Slow growing, encapsulated tumor arising in association with nerve trunk It pushes the nerve aside as it grows. Asymptomatic, tender in some instances Common in young and middle aged adults Range from a few millimeters to several centimeters in size

19. Tongue is the most common location Occasionally arise within bone Pain and paresthesia present in intrabony tumors

20. NF2 – caused my mutation of tumor suppressor gene NF2 which codes for protein merlin Schwannomatosis related to mutation of SMARCB1 gene.

21. Histopathology Encapsulated tumor demonstrating two microscopic patterns in varying amounts Antoni A and Antoni B Streaming fascicles of spindle shaped Schwann cells – Antoni A Form palisaded arrangement around central acellular, eosinophilc areas known as Verocay bodies.

22. Verocay bodies contain reduplicated basement membrane and cytoplasmic processes. Antoni B – less cellular and less organized and spindle cells randomy arranged within loose, myxomatous storma

23. Degenerative changes seen in older tumors containing hemorrhage, hemosiderin deposits, inflammation, fibrosis and nuclear atypia. Plexiform schwannoma another variant – multinodular plexiform growth pattern. May be associated with NF2 or Shwannomatosis

24. Treatment Treated by surgical excision Malignant transformation is very rare

25. Malignant peripheral nerve sheath tumor Malignant schwannoma, neurofibrosarcoma, neurogenic sarcoma Malignancy of peripheral nerve origin Common in proximal portion of extremities and trunk

26. Clinical and radiographic features Common in young adults. Mean age 29-36 years Enlarging mass that exhibits rapid growth. Associated pain or nerve deficit is common Oral tumors may occur anywhere Most common sites are mandible, lips and buccal mucosa Radiographic examination of intraosseous tumors reveal widening of mandibular canal or mental foramen with or without irregular destruction of surrounding bone

27. Histopathologic features Fascicles of atypical spindle shaped cells resembling fibrosarcoma More irregular in shape with wavy or comma shaped nuclei. Less cellular myxoid areas also may be present. With some tumors heterologous elements including skeletal muscle differentiation (triton tumor), cartilage, bone or glandular structures

28. Treatment Radical surgical excision along with radiation and chemotherapy. Prognosis is generally poor especially in patients with neurofibromatosis type I