Saiag et al listed a number of criteria for diagnosis of regional lymph node metastases from a malignant melanoma on ultrasonography. This can be a reliable method if stringent criteria are used.
Major criteria:
(1) circular or oval hypoechoic lymph node
(2) Solbiati Index < 1.5 (ratio of longitudinal dimension to transverse dimension, indicating that the node is more circular)
(3) hilum not hyperechoic
Minor criteria:
(1) nodular hypoechoic focus within the lymph node
(2) irregularity to lymph node margin
Interpretation
Called Positive If
stringent
all 3 major criteria present
nonstringent
>= 1 major AND >= 1 minor criteria present
Performance:
• The stringent criteria had a sensitivity was 77% and specificity was 98%.
• Use of the nonstringent criteria did not change sensitivity but lowered specificity because of increased numbers of false positive diagnoses.
• Ultrasonography was more sensitive and marginally more specific than palpation on physical exam.
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