Genitogluteal Porokeratosis: 10 Years to Make the Diagnosis!

Abstract

Genitogluteal porokeratosis, a relatively rare presentation of porokeratosis of Mibelli, often manifests in an atypical way due to its verrucous appearance that may obscure the characteristic annular keratotic rim. For this reason, misdiagnosis as other common papulosquamous diseases is not uncommon. We report a 44-year-old man with a 10-year-history of slowly progressive pruritic psoriasiform/lichenified plaques over the buttocks. Despite multiple skin biopsies, the lesions were misdiagnosed as psoriasis, lichen simplex chronicus, pityriasis rubra pilaris, and mycosis fungoides, until the last biopsy revealed findings characteristic of porokeratosis. Dermatologists and dermatopathologists should be aware of this rare and unique variant of porokeratosis, which, in addition to the atypical clinical presentation and the occasional misleading histology, may portend a better prognosis in terms of malignant degeneration.

Pigmented Porokeratosis. A Further Variant?

“…The reported incidence of porokeratosis-associated malignant transformation is approximated at 7.5% with linear variant being the most frequently affected and squamous cell carcinoma being the most common cancer. 1,16 There is no mention of the association between malignant transformation in porokeratosis and increased pigmentation. None of the cases in Shumack's series had histological evidence of malignant change.…”

Genitogluteal porokeratosis - Case report

“…7 Although affecting similar locations, with clinical features that can be histologically superimposable, the ptychotropic form presents an unique feature that is the presence of multiple cornoid lamellae 7,8 , not detected in this case. Therefore we preferred the term genitogluteal porokeratosis to encompass both the clinical and histopathological findings of this case.…”

Perineal warty plaques

“…[ 7 ] Moreover, psoriasiform hyperplasia, hyperkeratosis, dermal telangiectasia, and papillomatosis are few other features seen that often add to the already pronounced confusion of clinical similarity with psoriasis. [ 8 ] Several cases have also been reported with cutaneous amyloid deposition secondary to frequent rubbing and scratching caused by itch. [ 1 ] A noteworthy issue is the presence of dyskeratotic cells overexpressing p53 gene underlying the cornoid lamellae, indicating the role of tumor suppressor gene in its pathogenesis.…”

“…[ 1 ] A noteworthy issue is the presence of dyskeratotic cells overexpressing p53 gene underlying the cornoid lamellae, indicating the role of tumor suppressor gene in its pathogenesis. [ 8 ]…”

“…Close follow-up is necessary, for there is a yet uncertain risk of malignancy given the known risk of 7%–11% with porokeratosis, mainly squamous cell carcinoma, and also Bowen disease and basal cell carcinoma. [ 8 ] Although no such transformation has yet been reported with verrucous porokeratosis, this figure can run as high as up to 24% in porokeratosis in patients with risk factors (linear variant, long-standing large lesion, late onset, old age, and history of prior radiation exposure). [ 14 ] Verrucous porokeratosis is known to run a long course before being adequately diagnosed, and so need to be monitored to look for any possible malignant degeneration.…”