Teaching Case

Skin lesion (2 centimeters of the largest transverse diameter) clinically suspected to be a melanoma before surgical reject.

Skin lesion (2 centimeters of the largest transverse diameter) clinically suspected to be a melanoma before surgical reject. A morphological sonographic study was performed to analyse the structural sonographic pattern and to mesure tumor thickness with electronic calipers. The maximal thickness was determined by measuring from the stratum granulosum to the deepest point on the posterior margin. High frequency US scan demonstrates an ovoid hypoechoic tumor with homogeneous echostructure and well-defined lower and lateral margins. The tumor measured: 2.60 mm in thickness (20 MHz) 2.72 mm in thickness (13 MHz) Color Doppler sonography was used to search for intratumoral vessels and completed by a spectral analysis with determination of the resistive index (RI = systolic velocity - diastolic velocity / systolic velocity). The low resistance intra tumor blood flow caracterize the neovascularization. Color Doppler sonography scan reveal a tumor containing intratumor vessels. The arterial velocity spectrum shown below the scan was recorded. The resistive index was low : 0.41

Naevus Current management of melanoma consist in a first surgical resection based on the clinical features followed in about 30% of cases by re-excision according to the Breslow index measured at histological analysis. Surgical margins (according to the french consensus) .must be adapted to the tumor thickness: a marging of at least 1 cm is required for tumors with a Breslow index of 1 mm or less, of 2 cm for those with an index between 1.01 and 4 mm and of 3 cm for those with an index over 4 mm. At histologic analysis, the tumor measured 2 mm in thickness (Breslow index).The overestimation of tumor thickness at US occurrred when a melanoma is developing inside a neavus Also, Color Doppler is able to evaluate angiogenesis and pulsed Doppler characterize the tumor vascularisation of melanoma.