Evaluation of Ultrasound Biomicroscopy in the Local Staging of Cutaneous Melanoma

Cutaneous melanomas represent 4 to 11% of cutaneous cancers, but is responsible for 75% of the deaths reported for these pathologies. The incidence rate double every 10 years. Fourteen thousand cases and 1700 deaths were reported in France in 2015. The local staging of the cancer is represented by the Breslow index, which is measured on histological analysis, corresponding to the maximum depth of the cancer. Breslow index is a good pronostic value, and is used to choose for the best treatment for the patient. Having access to the Breslow index before the first resection of the tumor would allow dermatologists to make a complete resection with the best treatment, and the analysis of the sentinel lymph node, all during the same surgical time. Currently, patients need 2 surgeries : one before the Breslow index, and a second one after. The depth of cutaneous melanoma was already evaluated with High-Frequency Ultrasound (HF-US), but gave disappointing results, with Breslow index not being accurately measured. Only 50% of tumors less than 2mm depth were efficiently measured. Results were even worst for bigger tumors. Ultrasound biomicroscopy (UBM) is a new approach, depending on the use of ultra high frequency and large-band transducer. Nice's CHU acquired the only ultrasound device capable of applying such ultra high frequency ultrasound (UHF-US) to human tissues. The device is a VEVO MD (Vevo MD, Toronto, Canada) and equip the Ultrasound Department since June 2018. The images investigators can assess with this device have an axial resolution of 30µm, for a maximum emission frequency of 70MHz, which was not attainable until this day in human care. Furthermore, when compared to some of the mono-frequency devices investigators experimented before, this device allow investigators to attain a maximum depth of analysis up to 8mm. In consequence, this device seems to be able to realize an extremely precise analysis of the skin, and of the cutaneous melanomas, for a structural analysis, as well as a precise depth measurement, and should be evaluated in the measurement of the Breslow Index. The objective of the study is to analyze the interest of ultrasound biomicroscopy in the pre-therapeutic evaluation of the Breslow index of cutaneous melanoma, compared to histological findings. The study will include 60 patients with cutaneous melanomas, recently diagnosed in the Dermatology Department of the Nice University Hospital (Pr Bahadoran, Pr Passeron, Pr Lacour). Each patient will beneficiate from complete Ultrasound biomicroscopy analysis of the tumor The examination will be made blindly by 2 operator, both with experience in Ultra High frequency Ultrasound examinations (Dr Azulay, Dr Raffaelli). The maximum depth of the melanoma (Breslow index) will be recorded in µm. After surgical resection, the histologic analysis (Dr Long, Pr Hofman, Clinical and Experimental AnatomoPathologic laboratory, Nice's University Hospital) will measure the gold-standard Breslow Index. The comparison will analyze the capacity of Ultrasound biomicroscopy for a precise measurement of the Breslow Index, as well as the inter and intra-operator concordance. If the results of this study are positives and suggest a modification of the therapeutic strategy, a larger multicentric study would be launched in the near future.