Intraoperative imprint cytology in assessment of sentinel lymph nodes and lumpectomy surgical margins.

Intraoperative imprint cytology (IIC) in the assessment of sentinel lymph nodes (SNs) allows immediate, cost-effective axillary lymph node dissection. IIC diagnosis is accurate in up to 100% of grossly abnormal SNs. Despite overall low sensitivity for grossly negative SNs, the benefits of immediate complete axillary lymph node dissection offset the increased risk of missing micrometastases or loss of isolated tumor cells (ITCs) by performing frozen section. IIC of the lumpectomy margins is rapid, accurate, and cost effective. It allows re-excision during initial surgery if needed with better cosmetic result. It is a useful adjunct to, and frequently a replacement for frozen section in many centers. Cytopathologists must familiarize themselves with both advantages and pitfalls of IIC to avoid errors.