BENIGN NEURAL TUMORS OF THE ORAL CAVITY - A COMPARATIVE IMMUNOHISTOCHEMICAL STUDY

To determine if immunohistochemistry can be used as adjunct to the dia gnosis and classification of oral benign neural tumors, we stained 77 neurally differentiated tumors with a panel of neural-associated antib odies (S-100 protein, CD57, epithelial membrane antigen, factor XIIIa, CD34; CD68, collagen IV). Using standard histologic criteria, we iden tified 13 schwannomas, 16 neurofibromas, 23 traumatic neuromas, 16 pal isaded and encapsulated neuromas, and 9 granular cell tumors from arch ived oral pathology specimens. Silver stains showed that neurofibromas , traumatic neuromas, and palisaded and encapsulated neuromas consiste ntly contained axon filaments. Although all neural tumors contained S- 100-positive cells, schwannomas and palisaded and encapsulated neuroma s contained the most. All tumors expressed CD57; traumatic neuromas we re stained intensely and the others stained weakly. The consistent epi thelial membrane antigen capsular staining of schwannomas and the abse nce of factor XIIIa-positive dendritic/spindle cells helped distinguis h these tumors from others. Many CD34-positive cells were found in sch wannomas, and few were found in palisaded and encapsulated neuromas. V ariable numbers CD68-positive cells were seen in all neural tumor type s; some of these cells appeared to be macrophages and mast cells, but many were thought to be Schwann cells expressing this antigen. Collage n IV staining, apparently representing basement membrane, was generall y a feature of all benign neural tumors. The immunophenotype of the gr anular cells of the GCTs was S-100+, CD57+, and collagen IV+ supportin g the putative neural origin of these tumors. We conclude that neural origin/differentiation of a connective tissue tumor can be confirmed w ith stains for S-100 protein, epithelial membrane antigen, CD57, and c ollagen IV. Staining patterns and intensities associated with the pane l of antibodies tested can be useful in tumor classification.