Differentiating moles from melanoma

Differentiating moles from melanoma

14 July 2017

Melanomas are often hard to differentiate from moles, making early recognition a challenge for many doctors and patients. Surgery is in fact required to confirm a diagnosis of melanoma.

One way that melanoma is differentiated from moles is by observing a change in shape or colour, as melanoma cells are continuously dividing. When we monitor a lesion with close-up photography, known as dermoscopy, over three months most moles will not change whereas most melanomas will change. This technique is known as short-term dermoscopy digital monitoring.

A new technology for diagnosing melanoma has been developed to improve clinical accuracy. Electrical impedance spectroscopy (EIS) is a non-invasive diagnostic technique that evaluates the lesion by applying alternating electric current. There are electrical differences between benign well-organised moles and malignant chaotic melanomas.

Researchers at Melanoma Institute Australia recently evaluated this technology to see if a lesion with a low score using EIS could be dismissed as completely benign and not need monitoring. They also evaluated if a lesion with a very high score should be removed immediately, avoiding unnecessary and potentially dangerous delay.


The researchers found that using EIS can avoid the need for follow up in just under half of all cases. They also noted that using EIS the first time a patient is monitored can enable early excision of a melanoma without the usual delay of 3-monthly monitoring. This was the case in 83% of all the melanoma cases studied.

Publication: Rocha L, Menzies SW, Lo S, Avramidis M, Khoury R, Jackett L and Guitera P. Analysis of an electrical impedance spectroscopy system in short-term digital dermoscopy imaging of melanocytic lesions. Br J Dermatol. 2017 Apr 19. doi: 10.1111/bjd.15595. [Epub ahead of print]