A man presents with a painless nodule on his arm that developed over recent months. What dermoscopic features are helpful in diagnosing this lesion?
A 63-year-old office worker presented with a painless nodule on his right upper arm that had arisen in recent months. The lump had not been present five months earlier when he attended for his most recent full skin examination. He had fair skin with many solar lentigines, moderate numbers of actinic keratoses and few naevi, none of which were dysplastic. There was a past history of three nonmelanoma skin cancers, all on sun-exposed sites, and a family history of melanoma affecting his mother.