Touch Imprinting Cytology may be useful in the intraoperative evaluation of the sentinel lymph node in melanoma

The aim of the study was to assess whether the reliability of Touch Imprinting Cytology (TIC) of Sentinel lymph node biopsy (SLNB) in skin melanoma patients allows intraoperative decisions regarding simultaneous radical lymphadenectomy to be made. Previous experiences have shown that the limit of TIC in extemporaneous diagnosis was represented by the minimal deposits of the tumor. Many current data seem to show that in this situation radical lymphadenectomy is no longer necessary, so we wondered if TIC could regain importance in the intraoperative management of these patients.

TIC results of Sentinel Lymph Nodes Biopsy (SLN) were compared with those of standard histopathological and immunohistochemical examinations.

A total number of 110 SLN were detected from 50 melanoma patients.TIC revealed the presence of metastases only in 1 out of 13 melanoma-positive SLN (sensitivity 7.6%). There were no false-positive results of TIC (specificity 100%). The negative predictive value was 75.5%, the positive one 100% with a total diagnostic accuracy of 76%.

TIC for SLNs is a reliable method, relatively fast and not very expensive. Although with a very high specificity, its sensitivity was very low, and almost exclusively limited to macro-metastases (>2mm). Furthermore, it was not possible to identify a subgroup of patients, based on the characteristics of the primary tumor, in which the method could have been more useful. Finally, even in positive cases, the method rarely reduced the need of a tactic in two stages, principally for the management of the operating room.

Melanoma, Sentinel lymph node (SLN), Touch Imprinting Cytology (TIC).