The purpose of this study is to describe melanotic tumours and the pathogenesis of these tumours. The focus of this study is on differences between benign and malignant tumours as well as the prognosis one may expect when diagnosing this disease. The mechanisms responsible for the occurrences of the tumours are not yet fully understood. It is believed that factors such as chronic trauma, infections, medications and hormones affect the cell mechanisms in some way. Determinants of the malignancy of the tumour are not completely known.