ABSTRACT
INTRODUCTION The tumors discussed within this chapter arise from epithelial cells differentiating toward adnexal structures, except for Merkel cell tumor, which is considered to be a primary neuroendocrine carcinoma of the skin. The derivation, classification, and nomenclature of the adnexal tumors are controversial, and important disagreements will be addressed. This chapter is organized into subunits based upon tumoral differentiation toward hair, sebaceous glands, apocrine glands, and eccrine glands, with the final section discussing Merkel cell carcinoma.
