Clarifying the cellular composition of benign peripheral nerve sheath tumors

Abstract EN

Background :To clarify the cellular composition of various peripheral nerve sheath tumor lesions, expression of S100 protein and CD34 were immunohistochemically investigated.

CD34- positive cells have recently been reported in normal nerve and neural tumors.

Aim : This work aimed at determining whether CD34 expression in benign nerve sheath lesions was found in a unique cell population or in a subset of nerve sheath cells.

Material and Methods : Immunohistochemical staining was performed using a standard avidin-biotin complex method with two separate color developing system ; Forty neurofibromas and 16 neurilemomas (56 cases ) were studied.

Results : All lesions strongly expressed S100 protein in both nuclei and cytoplasm.

CD34 was detected in cells having dentritic cytoplasm present in greatest number in Antoni B zones of neurilemoma, myxoid zones of neurofibromas, at the periphery of lobules in both tumors types and condensed in apposition to perineurium.

The CD34 positive cells were also detected in normal nerves.

They were infrequent in Antoni A zones of neurilemomas.

No dual S100 / CD34 expression was seen in any of the 56 cases tested.

Conclusions :This double immunostaing confirms the presence of a CD34 reactive non-schwannian cell type in these neural neoplasms.

The CD34 positive / S100 negative cell population is present also in normal nerves and infrequently seen in the areas of cellular neoplastic schwann cells.

CD34 positive / S100 negative cells in peripheral nerve sheath tumors most likely are non-neoplastic and may serve supportive functions.