Accuracy of real-time ultrasound elastography in the differential diagnosis of lymph nodes in cutaneous malignant melanoma (CMM): a pilot study

We investigated the diagnostic ability of real-time elastography to differentiate between reactive and metastatic lymph nodes in cutaneous malignant melanoma (CMM) patients and to determine the optimum cutoff value for elastography scores for diagnosis CMM. Twenty lymph nodes (metastatic, n = 13; reactive, n = 7) from 12 patients with CMM were examined by both elastography and B-mode ultrasound in this prospective study. Elastographic patterns were given scores of 1-5 according to the percentage of high elasticity (hard) areas in the lymph node. Elastographic patterns 1, 2, 3, 4, and 5 were assigned elastography scores (ES) of 1, 2, 3, 4, and 5, respectively. B-mode ultrasound diagnosis was performed on the basis of the morphological patterns (balloon-shaped lymph node and loss of central echoes). The sensitivity, specificity, and accuracy were calculated, and receiver operating characteristic analysis was performed, comparing with elastograms and B-mode images, with histological findings as the reference standard. Sensitivity, specificity, and accuracy of elastography were 100, 71, and 90 %, respectively, with an ES cutoff value of 3; 92, 100, and 95 % for elastography with an ES cutoff value of 4; and 77, 57, and 70 % for B-mode ultrasound. Elastography can enhance the diagnostic accuracy of ultrasound for differentiating between reactive and malignant lymph nodes in CMM and might eliminate the need for sentinel lymph node biopsy. The optimum ES cutoff value for reactive versus metastatic lymph nodes is 4.