Benign and malignant tumours of skin appendages

Most physicians and other non-dermatologists are aware of common skin cancers – basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and malignant melanoma (MM) – but if asked about tumours of skin appendages, they may appear rather puzzled. This is not surprising as this group of tumours is uncommon; additionally, they have long, complicated names which are derived from Greek or Latin and as such are easily forgettable. The situation is difficult as there is no consensus agreement as to the best classification and nomenclature system, even among experts. However, tumours of skin appendages, also known as appendicular, appendageal or adnexal tumours, constitute a huge but important group and in one major textbook, 36 different types are listed. In this article, we will aim to clarify them by applying basic principles and illustrating some of the more common examples.