At least one other US examination was performed at least 12 months after the first one. The exclusion criteria were: drop out from the control visits; presence of metastatic lymph nodes; occurrence of other neoplastic lesions

during the follow-up, including those of different histotype with respect to melanoma, in areas theoretically drained from the lymph nodal station being studied; a second surgical procedure in the same area; loco-regional dermatological or inflammatory pathologies (e.g., psoriasis, pemphigus etc) and pregnancy. The characteristics of the study AZD2014 population are shown in Table 1. Table 1 Characteristics of the study population Number of patients 124 Sex Males: 50; Females: 74 Age (in years, mean ± SD) 55.3 ± 13.81 (Min 12; Max 83) Thickness of Superficial Spreading Melanoma (mm) ≥0.7; ≤1.3 Diabetes click here mellitus 8.06% of the sample population Recent local trauma 9.67% of the sample population Hair removal 38.71% of the sample population SD: standard deviation. A total of 124 individuals (74 females

and 50 males) were included in the study; they ranged in age from 12 to 83 years (mean age of 55.3 years and modal age of 55.5 years). The melanoma thickness, which we measured for descriptive purposes only according to the Breslow criteria, ranged from 0.7 to 1.3 mm. We carefully chose the station contralateral to the site of the excised lesion and the sentinel node, to reduce the possibility of contamination from post-surgical

interference and the statistical probability of metastases. The same US apparatus was used for all patients (Esaotebiomedica Mylab 70XVG – Genova, Italia), and a 7.5-13 MHz linear array probe (type LA523) was adopted in all cases. All of the US examinations were performed by two expert radiologists (FMS and FE), who have, respectively, 35 and 12 years of experience in US activity and 12 and 6 years of experience in the field of dermatological oncology. The US examination was performed with the patient in a supine position, with the examined limb outwardly rotated and abducted, exercising sufficient very pressure with the probe and, if necessary, varying the frequency based on the patient’s somatic habitus. We first performed a normal scan of the vascular axis and in all cases at least a second longitudinal scan, thus measuring two major orthogonal planes of the lymph node. The data were recorded on a previously developed form (Additional file 1: Attachment), and the images were recorded in our facility’s RIS-PACS system; if there were any doubts, the authors reviewed the data together to reach a consensus; if necessary, a third party was involved in reviewing the data.