An unusual spiculated presentation of follicular porokeratosis

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.…”

“…Speculatively, UV radiation might be involved in pathogenesis, as some cases displayed worsening with sun exposure or developed over sunexposed sites [524,525,529,533,534]. In a patient with Sturge-Weber syndrome, FP caused secondary alopecia due to follicular hyperkeratosis and perifolliculitis [528]. Currently, no malignancy has been reported in FP.…”

“…Differential diagnoses for FP include a wide range of entities: nevus comedonicus, lichen planopilaris, lichen nitidus, lichen spinulosus, follicular cutaneous T-cell lymphoma, follicular porokeratoma (porokeratotic acanthoma), trichodysplasia spinulosa, hyperkertotic spicules associated with paraproteinemia, keratosis pilaris, phrynoderma and paraneoplastic spiny keratoderma [528,532]. Multiple minute digitate hyperkeratosis (filiform hyperkeratosis), presenting as hyperkeratotic spicules emerging from minute annular follicular and non-follicular plaques, is speculatively considered by some authors to belong to the same FP spectrum [538].…”

“…These included cryotherapy [529], topical steroids [526,533], topical pimecrolimus cream (twice per day; 2 months) [539], topical 5-FU (twice per day; 4 months) [530], imiquimod 5% cream (1 case treated once per day for 2 weeks) [532,533], cholesterol/lovastatin ointment (unknown concentration and regimen) [530], tretinoin cream [528] and ketoconazole shampoo [528]. No effect was achieved with systemic treatment with oral hydroxychloroquine (200 mg twice per day) [526] and acitretin (unknown regimen) [528]. Moreover, the latter led to the development of abscesses and spiculisation, aggravated xerosis and itch.…”