27. Assessment of periaxin expression in human peripheral nerve sheath tumours and related lesions

Periaxin is a newly described protein that is expressed in myelinating Schwann cells. In developing and regenerating nerves, periaxin is predominantly localised to the adaxonal surface of Schwann cells as they begin to form compact myelin. In adult nerves, peraxin is expressed by myelinating Schwann cells and localised to the abax-onal surface. Its localisation changes dynamically during ensheath-ment and myelination. Periaxin is expressed in devil facial tumour disease (DFTD), a transmissible cancer that is threatening the survival of the Tasmanian devil ( Sarcophilus harrisii) . DFTD cells express proteins characteristic of myelinating Schwann cells, including periaxin. A useful diagnostic marker for DFTD is expression of periaxin. We investigated the expression of periaxin in a variety of human peripheral nerve sheath tumours and related lesions such as schwannomas, neurofibromas, traumatic neuromas, solitary circumscribed neuromas, malignant peripheral nerve sheath tumours and granular cell tumours. Several different human tissue controls including bowel, gallbladder, smooth muscle neoplasms, naevi and melanoma were also used. The expression of periaxin was compared with a range of proteins associated with nerve tissue including S100, neurofilament, EMA and CD34. We conclude that periaxin, correlates most closely with neurofilament expression, in schwannomas, neurofibromas and normal nerve tissue controls. Periaxin does not appear to have an additional role in the diagnosis of human peripheral nerve sheath tumours and related lesions.