Doppler ultrasound as an adjunct to the differential diagnosis of pigmented skin lesions.

One hundred and forty-one pigmented skin tumours were examined with a 10 MHz ultrasound Doppler flowmeter to investigate the value of detecting blood flow in the diagnosis of raised pigmented skin lesions. Most of the benign lesions except for those with an angiomatous basis were devoid of blood flow signals while all basal cell carcinomas and 96 per cent of thick melanomas (greater than or equal to 0.9 mm) were associated with detectable Doppler frequency shift signals. While the characteristics of analysed Doppler waveforms are of research interest, the simple detection of blood flow by a hand held instrument gives sufficient information for clinical purposes. In practice this simple test has been sufficiently reliable to prove a useful adjunct in the diagnosis of raised pigmented skin lesions. It has been found particularly helpful in the common clinical problem of differentiation of nodular melanoma from basal cell papilloma and benign intradermal naevus. If such a lesion is thought to be benign, and has detectable flow signals, one should reconsider the diagnosis. Absence of flow signals is strong confirmation of a benign clinical diagnosis. The test should be regarded as an adjunct to clinical diagnosis since, in common with all noninvasive diagnostic techniques, false negative and false positive cases will be encountered. The technique is not appropriate to macular lesions since these are usually flow negative, irrespective of the pathology.