Value of planar lymphoscintigraphy (PL) versus SPECT/CT in evaluation of sentinel lymph node in trunk melanoma - one center, large series retrospective study.

BACKGROUND: Localization and histopathological examination of sentinel lymph node is a standard of melanoma treatment. The first stage of identification of the SLN is the preoperative lymphoscintigraphy. The aim of this study was to assess and compare diagnostic value of planar lymphoscintigraphy and SPECT/CT in sentinel lymph node biopsy procedure performed in patients with cutaneous trunk melanoma.

MATERIAL AND METHODS: Between 2015 and 2016, patients with trunk melanoma (N = 255, F/M 95/160), aged from 17 to 88 after an excisional biopsy, with primary tumor ≥ pT1b (AJCC 2009, median Breslow thickness 2.0 ± 3.13) were included in the study. In all the patients PL was followed by SPECT/CT 1-3 hours after injection of 99mTc- colloid particles, and SLNB was performed the next day.

RESULTS: SPECT-CT revealed 78 (18.6%) SLN more than PL, and in 40 patients showed additional lymph drainage regions leading to surgical adjustments. In 18 patients (7.1%) SPECT-CT revealed SLN not visible in the PL (false-negative PL) and in 22 patients (8.6%), foci of uptake interpreted in PL as hot SLNs were found to be non-nodal sites of uptake when assessed on SPECT/CT (false positive PL). SPECT-CT vs. PL mismatch was observed in 31 patients (12.2%) and was the most common in patients with primary lesions located in the anterior inferior medial region (75%).

CONCLUSIONS: Results of the presented study indicates the high diagnostic value of SPECT-CT in assessment of SLNs and proved that SPECT-CT increases the sensitivity and accuracy of SLN identification as compared to PL even in very experienced hands.