Ultrasound morphology of inguinal lymph nodes may not herald an associated pathology

Among patients undergoing follow-up after surgery for melanoma, ultrasound (US) very often reveals lymph nodes in groin area, that do not show clear characters of a metastatic lesion yet that have atypical US features, which could result in diagnostic uncertainty. We evaluated such lesions among a cohort of patients.

The study population consisted of patients who presented consecutively to our facility for a control between 1 January 2009 and 30 July 2010 and who had undergone surgery for a melanoma, at least 6 months earlier, in areas draining to lymph nodes of the groin but choosing – for this study - the opposite side to the natural drainage. The following parameters of the US performed on the lymph nodes were evaluated: number and size, aspects of the outline, including any extroflexion of the outline and contours morphology, homogeneity and thickness of the cortex and aspects of the hilus, characteristics of the vascularisation of the lymph node at color-power Doppler. A second US examination was performed on the same area after at least 12 months.

We found a very high number of patients (42/124) with lymph nodes that did not appear to be fully normal at US examination, particularly those with structural alterations in the hilus and slight loss of physiologic curvature of the outlines, with moderate thickening of the cortex. Of the 124 patients, who were followed for at least one year, 42 showed these characteristics, and none of these showed any progression to malignancy at follow-up. Based on these results, we can conclude that focusing excessively on such US findings could lead to the inappropriate performance of additional diagnostic tests, with a consequent increase in management costs and a worsening of the quality of life for these patients.