SENSITIVITY AND SPECIFICITY OF ANTIBODIES ON NECROTIC TUMOR-TISSUE

Immunohistochemistry occasionally is used to determine the lineage of entirely necrotic tumors. However the sensitivity and specificity of a ntibodies on necrotic tissue are unknown. To determine the usefulness of immunohistochemistry with necrotic lesions, a series of 24 known tu mors consisting of 14 carcinomas, 2 lymphomas, 2 melanomas, and 6 sarc omas (all with extensive necrosis) was examined for reactivity with 6 cytokeratin antibodies, S100, and LCA. Carcinomas stained positively w ith at least I cytokeratin antibody in 78% of the cases. The cytokerat in antibodies with the highest sensitivity were AE1, AE1/3, S903, and PANCK. These antibodies also retained specificity for epithelial diffe rentiation; no reactivity was observed in the 10 necrotic nonepithelia l tumors. LCA retained its reactivity with necrotic lymphoma, but S100 reacted with only one third of the necrotic lesions. Unexpectedly, re activity for LCA and S100 occurred in some necrotic carcinomas. Kerati n markers can be used on necrotic tissue to determine epithelial diffe rentiation, but the results obtained with S100 and LCA on necrotic tis sue should be interpreted with caution.