A 60-year-old Caucasian female presents with a dark spot on the third toe of her left foot. 

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<p>A 60-year-old Caucasian female presents with a dark spot on the third toe of her left foot.</p><p>The lesion is located on the frontal aspect of the skin under the nail. It is completely asymptomatic, and owing to its unusual</p><p>location, the patient is unsure how long the lesion has been present. She only recalls having had a pedicure a week ago and experiencing pain when her nail was being clipped.</p><p>On examination, there is a well-demarcated, irregularly shaped pigmented macule.</p><p>Under dermoscopy (pictured), the macule has a brown colouration with a homogeneous pattern. Both localised and satellite globules can also be seen.</p>

Professor Dedee Murrell is head of dermatology, St George Hospital; professor, faculty of medicine, UNSW Sydney; and honorary professorial fellow, The George Institute for Global Health, Sydney, NSW.