Follicular porokeratosis: four new cases

Abstract

Porokeratosis, a disorder of keratinisation, is clinically characterized by the presence of annular plaques with a surrounding keratotic ridge. Clinical variants include linear, disseminated superficial actinic, verrucous/hypertrophic, disseminated eruptive, palmoplantar and porokeratosis of Mibelli (one or two typical plaques with atrophic centre and guttered keratotic rim). All of these subtypes share the histological feature of a cornoid lamella, characterized by a column of 'stacked' parakeratosis with focal absence of the granular layer, and dysmaturation (prematurely keratinised cells in the upper spinous layer). In recent years, a proposed new subtype, follicular porokeratosis (FP_, has been described, in which the cornoid lamella are exclusively located in the follicular ostia. We present four new cases that showed typical histological features of FP.

Follicular Porokeratoma: Report of a New Variant of Porokeratoma (Porokeratotic Acanthoma) and Literature Review

“…11 This is reminiscent of the rare cases of follicular PK, a PK variant with CL present exclusively within hair follicles. [14][15][16][17] By analogy with these rare PK forms, we have termed this case "follicular PKM." It is tempting to speculate that the follicular involvement in the PKM of our patient was triggered, at least in part, by the episode of folliculitis that preceded the development of the lesion, as the patient recalled.…”

Porokeratoses—A Comprehensive Review on the Genetics and Metabolomics, Imaging Methods and Management of Common Clinical Variants

“…FP presents with a wide range of clinical phenotypes [408,527,528]. Small (usually <1 cm in diameter), static, either itchy or asymptomatic, well-defined, erythematous, violet, pinkish, skin-coloured, brownish or dusky folliculocentric papules and/or nodules with a raised keratin rim may localise on sun-exposed and sun-unexposed sites (excluding the palms and soles) [241,[525][526][527][529][530][531][532], and occasionally may be accompanied by follicular spicules [523,528]. Rare, limited FP cases with exclusive nasal skin [531,[533][534][535][536] or scalp involvement [537] were also reported.…”