Immunocytochemistry (ICC) proved to be an essential adjunct in the fine-needle aspiration (FNA) cytological diagnosis of
chordoma of the clivus in a 62-year-old woman. The cytological picture in routinely stained smears was not entirely diagnostic for
chordoma due to the paucity of typical 'physalipherous' cells. To exclude other primary or metastatic
neoplasms of the skull base possibly sharing the same cytological picture, additional direct smears were immunostained with
antibodies specific for
cytokeratin (CK),
vimentin (VIM),
S100 protein (S100P), carcinoembrionic
antigen (CEA),
epithelial membrane antigen (EMA),
glial fibrillary acidic protein (GFAP),
CD68 antigen (KP1) and with the 'panepithelial'
antibodies B72.3 and Ber-EP4.
Chordoma cells showed the following immunoprofile: CK+/VIM+/S100P+/CEA-/EMA+/GFAP-/
B72.3-/Ber-EP4-/CD68+. The pattern of immunoreactivity for CK, S100P and CEA confirms previously reported data, while the
B72.3-/Ber-EP4-/CD68+ staining profile represents a novel observation. The detection of a CK+/S100+/CEA-/
B72.3-/Ber-EP4- immunocytological profile of
chordoma cells in aspirates is a basic requirement to exclude pertinent diagnostic differentials, such as metastatic
carcinoma,
ependymoma and
sarcoma, and permits a reliable pre-operative diagnosis of the tumour by aspiration cytology.