FISH Analysis of Chromosome 22 from Peripheral Nerve Biopsies of Intraneural Perineurioma (P05.146)

Abstract

Objective: We sought to evaluate for abnormalities in chromosome 22 in a large cohort of nerve biopsies of intraneural perineurioma using fluorescence in situ hybridization (FISH) analysis. Background Intraneural perineurioma is a benign hypertrophic peripheral nerve tumor presenting insidiously in young people with motor predominant mononeuropathy or plexopathy. There has been debate whether perineurioma is due to trauma or neoplasm. Abnormalities of chromosome 22 (as in other nerve sheath tumors) have been reported in one case of intraneural perineurioma suggesting clonal neoplasm. Design/Methods: The Mayo Clinic Cytogenetics Core hybridized and analyzed 28 paraffin embedded perineurioma tissues and two normal brain tissues. The FISH probe applied to each specimen localize to the DiGeorge/TUPLE1 gene regions located at 22q11.21 and the ARSA gene region located at 22q13. The tissues were probed and analyzed according to their marked H&E slides. Tissues were scanned to assess tissue morphology, hybridization efficiency and signal ratio. Once the tissue was scanned, signals from 100 nuclei were counted. Results: Twenty-six of 28 tissues were normal. One of 28 tissues was found to be abnormal with loss of ARSA at 22q13. The patient was a 35 year old man who presented with a 15 year history of gradually progressive tibial neuropathy. MRI demonstrated an enlarged sciatic nerve with T2 hyperintensity and enhancement. Fascicular nerve biopsy of the tibial division of the sciatic nerve was diagnostic of perineurioma. 1/28 tissues failed following several re-hybridization and set up attempts. Conclusions: Intraneural perineurioma is a focal hypertrophic peripheral nerve tumor of unknown cause. Based on previous studies, the cause of perineurioma may be due to abnormalities on chromosome 22. Our study demonstrated that rare cases may be due to loss of ARSA at 22q13 but this is not the major cause. FISH analysis of other regions of chromosome 22 is ongoing. Disclosure: Dr. Mauermann has nothing to disclose. Dr. Klein has received personal compensation for activities with Pfizer Inc as a consultant. Dr. Dyck has nothing to disclose. Dr. Engelstad has nothing to disclose. Dr. Flynn Gilmer has nothing to disclose. Dr. Jenkins has nothing to disclose. Dr. Dyck has nothing to disclose.