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

Abstract

Porokeratoma is a rare type of epidermal acanthoma, of which 22 cases have been published in the literature. It is characterized by the presence of multiple cornoid lamellae embedded within a single verrucous or keratotic nodule. Despite this histologic feature being shared with porokeratosis, the etiopathogenesis of porokeratoma and its relationship with porokeratosis remain unclear. We report a new case of porokeratoma involving hair follicles, a finding that has been reported in only one of the previously published cases. Analogous to follicular porokeratosis, a form of porokeratosis involving hair follicles, we have termed this lesion "follicular porokeratoma." A review of all 23 published cases (including the present case) is also provided.

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

“…Even though some researchers claim that porokeratoma is sporadic [543], the presence of PMVK mutation in porokeratoma [540] was recently confirmed by Zhang et al [15]. All porokeratomas studied in a genetic sequencing study on porokeratosis (5/134 index cases) demonstrated PMVK mutations (suggestively sporadic), confirming its clinical similarity to solitary VP and hyperkeratotic and classical PM [15].…”

“…Porokeratoma (porokeratotic acanthoma), introduced in a case series by Walsh et al in 2007 [540], is an isolated well-demarcated porokeratotic plaque or nodule deprived of the typical annular rim of scale, sometimes verrucous, hyperkeratotic, or depressed [1,[540][541][542], and predominantly involving the upper and lower extremities, followed by the buttocks, face and trunk [543]. Even though the majority of cases were solitary, multiple porokeratomas have also been reported [12,541,544,545].…”

“…Even though the majority of cases were solitary, multiple porokeratomas have also been reported [12,541,544,545]. The male to female ratio is 19:4, whereas the mean age of onset is 55 years (age range from 13 to 78) [543].…”

“…Porokeratoma is frequently misdiagnosed due to its substantial similarity to squamous cell carcinoma, basal cell carcinoma, actinic keratosis, psoriasis, seborrheic keratosis, papular amyloidosis (lichen amyloidosis), chromoblastomycosis, viral wart, prurigo nodularis, perforating dermatoses, digital mucous cyst and excoriation [541,543,545].…”

Human Papillomavirus-Associated Giant Clear Cell Acanthoma and Squamous Cell Carcinoma: A Rare Case Report and Literature Review

“…Conversely, Švajdler et al in 2016 examined the presence of α-HPV and β-HPV in extragenital/extraungual Bowen's disease, finding a considerable proportion of lesions positive for high-risk HPV types, which could imply the etiological role of HPV in these precancerous conditions [26]. The literature also discusses the potential benefits of HPV vaccination in preventing NMSC, with some evidence suggesting that a beta-HPV vaccine could serve as an adjuvant treatment measure for patients with recalcitrant NMSC [22,66,67]. The role of HPV proteins in cancer development was explored by Balaji et al in 2022, who reviewed the mechanisms through which HPV proteins, especially E6 and E7 oncoproteins, contribute to carcinogenesis [68].…”