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Linear lesions – 9 cases

From time to time, we come across linear skin lesions. This can be very helpful diagnostically as there is a limited range of possible diagnoses. A careful history and examination of the morphology of the lesions usually sorts them out.

For each of the nine 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 1

Epidermal naevus

Epidermal naevi (are developmental anomalies that follow the lines of Blaschko. Although often present at birth, they may appear later in childhood. Small ones consist of single or multiple parallel linear grey-brown warty plaques. Larger ones are linear on the limbs but tend to follow a predictable swirling pattern on the trunk. At times they are quite inflammatory (ILVEN or Inflammatory Linear Verrucous Epidermal Naevus). Incontinentia pigmenti and hypomelanosis of Ito are other less common ‘birthmarks’ that follow a similar linear and swirled arrangement. They are believed to be due to somatic mosaicism, but the exact mechanism has not yet been worked out.

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