Quiz
Blue skin lesions – 7 cases

Blue skin lesions may be due to melanocytic lesions, vascular lesions or exogenous pigment. Dermoscopy may be useful to distinguish them.

Melanin is normally a brown colour. Melanocytic lesions tend to be blue in colour if the melanin is located within the dermis. They may be congenital (e.g., mongolian spot) or acquired.

For each of the seven cases, study the image(s) and then answer the questions. You can click on the image to view a larger version if required.

Each case should take approximately 2 minutes to complete. There is a list of suggested further reading material at the end of the quiz.

Case 3

Name this blue-coloured skin lesion.

Metastatic melanoma

Describe the dermoscopic features

A growing nodule of any colour may be due to melanoma. In this case, the lesion was mistaken for a harmless blue naevus until the patient gave a clear history of growth. It was a metastasis; the primary had been removed several years previously.

The dermoscopy was not diagnostic as it was similar to blue naevus, but atypical vascularity on the periphery of the lesion is a clue to its malignant nature.

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