Several years ago, a middle-aged woman presented with a condition affecting her skin (photograph A) and mouth (photograph B), and she was diagnosed with lichen planus.

The patient then presented with dysphagia. A lesion was found high in the oesophagus (photograph C) and biopsy samples were taken (photograph D). Case question 1 WHAT IS THE AETIOLOGY OF THE STRICTURE? a) Benign b) Malignant