Scalp tumours. Gross specimen of a scalp with multiple tumours. This is a condition called eccrine spiradenoma. The tumours are benign and arise from sweat glands. They are soft and may be painful. This is a rare condition that usually occurs between the ages of 15 and 35. It is caused by a defective tumour suppressor gene. Tumour suppressor genes, when functioning properly, prevent cells from growing uncontrollably. Rarely the tumours may become malignant (cancerous). Treatment is with the surgical removal of the tumours. Once removed the tumours rarely reoccur.