title: Invaginated fibrokeratoma with matrix differentiation: a new histological variant of acquired fibrokeratoma.
abstract: We report two cases of acquired fibrokeratoma which present new clinical and histological features specific to the nail apparatus. There are three histological characteristics. (i) A deep epithelial invagination which develops from the proximal nail fold and is orientated in the same direction as, but is more proximal than, the normal matrix. (ii) The postero-inferior aspect of the cul-de-sac produced by the invagination acts as an accessory matrix, giving rise to a pseudo-nail plate. The granular layer is reduced or absent. (iii) This accessory nail apparatus lies on a conical dermal tumour, sharply demarcated from the surrounding dermis, with a wide base narrowing towards the tip. The finger-shaped structure is reminiscent of Kint's type I acquired fibrokeratoma.
authors.affiliation: Department of Pathology, Hôpital Pasteur, Nice, France.
authors.forename: C
authors.initials: C
authors.lastname: Perrin
authors.forename: R
authors.initials: R
authors.lastname: Baran
mesh_terms: D005260:Female; D005355:Fibrosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009260:Nail Diseases / Q000473:pathology*; D009262:Nails / Q000473:pathology*