Immunocytochemistry applied to aspiration biopsy cytology. Diagnostic contribution in 100 cases of previously...

To assess the contribution of immunocytochemistry (ICC) to aspiration biopsy cytology (ABC), in a diagnostic context, on routine, previously stained cytologic specimens.

Among 5,221 consecutive cases of ABC, 5.3% were subjected to ICC in the clinical-morphologic context. One hundred of these cases, with a final clinical and histopathologic diagnosis, were studied to determine the contribution of this ancillary technique to the final cytologic diagnosis. All cases had histopathologic study and prospective ICC, performed on usual smears, alcohol fixed and previously stained by the Papanicolaou technique, and were subjected to an avidinbiotin-peroxidase complex method.

ICC was contributory in 82% of cases. The contribution of ICC to ABC of lymphoid tissue, thyroid and related organs, soft tissue and miscellaneous cases was, respectively, 84% (39 cases), 88% (26), 72% (18) and 76% (17). ICC was noncontributory in 18 cases, due mainly to misleading interpretation (6%), uncharacteristic profile (5%) and inconclusive immunostain (7%).

ICC could be successfully applied in routine ABC specimens since the usually investigated antigenic determinants are preserved, allowing previous morphologic study and screening of the smears. The principal contribution of ICC applied to lymph nodes, thyroid and soft tissue aspirates was, respectively, confirmation of metastatic neoplasms, differential of follicular versus C-cell proliferation and assessment of mesenchymal lineages.