Predictive Value of Intraoperative Sentinel Lymph Node Imprint Cytology Analysis for Metastasis in Patients with Melanoma.

Since there are no standardized protocols regarding the detection of microscopic melanoma deposits in sentinel lymph nodes (SLN), the aim of this study was to present our experience with intraoperative cytological evaluation of SLN in patients with melanoma. The study included 475 SLN biopsies (SLNB) from 201 patients with primary cutaneous melanoma of intermediate thickness. Each lymph node was cut in half; touch imprint cytology (TIC) preparations of all cut surfaces were performed and stained according to a modified May-Grünwald-Giemsa method. The results were compared to definitive postoperative histology. Twenty of 25 SLNB positive on TIC proved to be metastatic when compared to definitive histology. Most of 32 SLN that were suspicious but not diagnostic on TIC were proven negative (23/32, 71.8%), while 7 nodes had metastases (one micrometastasis and one with isolated tumor cells only). The majority (94%) of SLNBs negative on TIC remained negative on final histology, while 6% or 25 nodes were positive, mostly with micrometastases or isolated tumor cells (17/25). In frozen sections performed in cases of suspicious or positive SLN cytology, metastasis was confirmed in 80% of positive and in 21.9% of suspicious TIC. Altogether, 49% (27/55) of positive SLNB were identified intraoperatively in 57% (24/42) of patients, and in those cases a complete regional lymph node dissection was performed in the first step. TIC assessment of SLNB with 99% specificity and 57% sensitivity for intraoperative identification of metastasis is useful and beneficial for avoiding a second operative procedure.