Case 19 Female, 39 years. Nodule, skin temporal region.Show diagnosis & comments
Compound naevus with lipomatous and osseous stromal metaplasia (‘osteonaevus of Nanta’), follicular keratostasis and granulomatous reponse to ruptured hail follicle
This naevus has led to a number of reactive changes in its stroma and adjacent tissues. Fat cells within a naevus are not uncommon; a focus of osseous metaplasia near (usually basal to) a naevus is less common: such naevi are sometimes called 'osteonaevus of Nanta'. Finally, there is a granulomatous response to keratin from a hair follicle, no doubt caused by keratostasis and folliculitis.