Paragangliomas of the head and neck: immunohistochemical neuroendocrine and intermediate filament typing

Twenty-nine paragangliomas of the head and neck region including 20 glomus jugulare (GJ) and nine carotid body (CB) tumors were evaluated for the presence of neuroendocrine and intermediate filament antigens. Immunohistochemistry on formalin-fixed, paraffin-embedded tissue was used to identify: S-100 protein (S-100); neuron-specific enolase (NSE); chromogranin A (CHA); serotonin (SER); synaptophysin (SYN); cytokeratin (CK); neurofilament (NF); desmin (DES); vimentin (VIM); and glial fibrillary acidic protein (GFAP). S-100 protein staining of sustentacular cell nuclei and cytoplasm was found in all tumors and was present in chief cells in 4 of 20 GJ and 3 of 9 CB tumors. All tumors stained with at least three neuroendocrine markers (29 of 29 NSE, 28 of 29 SYN, 26 of 29 CHA, 25 of 29 SER). CK was detected in 2 GJ and 1 CB tumor using anticytokeratins AE 1/3 and CAM 5.2. Neurofilament protein could not be demonstrated in fixed material, and all tumors were negative for GFAP and desmin. Vimentin was inconsistently detected in chief and sustentacular cells. We conclude that, in formalin-fixed material, paragangliomas have S-100 protein staining of sustentacular cells with chief cells containing antigens associated with neuroendocrine differentiation. The presence of CK in some paragangliomas is consistent with recent tissue culture studies demonstrating immunoblot confirmation of CK in pheochromocytomas and represents a potential source of immunohistologic misinterpretation in diagnosis, unless a panel of markers is utilized.