Intraoperative cytologic diagnosis of breast sentinel lymph nodes in the routine, nonacademic setting: a highly specific test with limited sensitivity.

Intraoperative determination of metastatic breast carcinoma in sentinel lymph nodes (SLNs) by cytologic methods has been proposed as highly specific and sensitive. Much of these data are derived from academic institutes with highly trained personnel and without axillary dissection occurring as a direct result of the intraoperative interpretation. This prospective study was undertaken to assess the sensitivity and specificity of cytology in the routine, private-practice, intraoperative setting. A total of 207 SLNs from 96 breast carcinoma patients were evaluated by intraoperative cytologic preparations by general surgical pathologists; positive results led to axillary lymphadenectomy. Ten nodes were positive by intraoperative cytology (IC). Permanent section analysis confirmed the presence of carcinoma in the IC-positive cases and documented carcinoma in 19 of the IC-negative cases. IC sensitivity and specificity were 34% and 100%, respectively. False-negative IC interpretations occurred in nodes with occult micrometastases (12 of 19 nodes) and lobular carcinoma (6 of 19 nodes). Only one of eight grossly positive sentinel nodes resulted in a false-negative IC. While near-perfect specificity and high sensitivity can be achieved with grossly positive sentinel nodes by IC, sensitivity is quite low in cases with micrometastatic and lobular carcinoma.