<p>This lady was promoted to come to clinic by a relative concerned by the appearance of this lesion. What is the diagnosis?</p>
<p>The most common blue lesion is a blue naevus. Some BCC have blue (or blue-grey) clods, and occasionally melanoma can be blue-black. This, however, is a giant comedone. <a href="http://www.pcds.org.uk/clinical-guidance/giant-comedone">Giant comedones</a> are essentially exceptionally large blackheads, only occasionally do they have a blue surround. Usually if you squeeze them the keratin core can be readily expressed. </p>
