Non-melanoma skin cancer: Appendageal tumours

Sudoriferous tumours represent approximately 1% of all primary cutaneous neoplasias. They have a variable, often unspecific clinical presentation and a wide histologic spectrum. According to their origin, cutaneous sweat gland tumours can be classified as eccrine, apocrine, eccrine and apocrine (mixed origin), or composite adnexal tumours. Further, they can be classified as benign or malignant, tumours of the sweat ducts or of the sweat glands secretory apparatus. Carcinomas of the eccrine and apocrine glands are neoplasms with infiltrative and metastatic potential. Some malignancies have benign counterparts from which they must be differentiated. Features that suggest malignancy include asymmetry of the lesion, invasion, irregular arrangement of neoplastic cells, cytonuclear atypia and pleomorphism, and significantly increased mitotic activity in the presence of abnormal mitotic figures. Other sweat gland carcinomas present differently from any benign tumour. Differentiating primary cutaneous sudoriferous carcinomas from metastatic carcinomas can often pose a serious challenge. Clinical history, histomorphological features, and immunohistochemical stains are all very important