Muciparous (goblet) cells occur in a small percentage of skin tumors of adnexal (sweat gland) origin, where they may produce a microscopic mucoepidermoid pattern. The great majority of these growths is benign. Phylogenetic considerations permit this phenomenon to be related to mucus secreting cells or glands in lower vertebrates and certain mammals. Ontogenetically related structures such as the mammary gland and stomodeal derivatives (salivary glands) may give rise to identical neoplasms. Experimental models are available in vitro and in vivo which demonstrate the ability of the vertebrate integument to undergo reversible mucinous differentiation under appropriate stimulation.
Zak FG, Palladino VS. Muciparous Metaplasia and Primary Mucoepidermoid Skin Tumors. Arch Dermatol. 1969;100(1):23-25. doi:10.1001/archderm.1969.01610250029006