Hypopigmented keratosis: is it a hyperkeratotic variant of idiopathic guttate hypomelanosis?

Abstract

We have occasionally seen patients with acquired well-demarcated, scattered hypopigmented papules. In this study, we investigated the clinical and histopathological characteristics of such lesions. Biopsies were taken from the lesional and perilesional normal skin from 10 of 13 patients, which were compared with 10 idiopathic guttate hypomelanosis (IGH) samples. The lesions were scattered, well-circumscribed, flat-topped, hypopigmented papules. There was no age or gender predilection. Marked hyperkeratosis was present, with clear-cut margins distinguishable from the adjacent normal epidermis. The melanin content was decreased in the lesional epidermis, which was associated with a decrease in expression of melanogenesis-associated markers such as tyrosinase and NKI/beteb (marker of gp100) and reduction in the number of melanocytes. These histological findings were similar to those of IGH except for the additional finding of a thicker stratum corneum in this case seem to represent a 'hyperkeratotic' variant of IGH.

Idiopathic guttate hypomelanosis-like macules co-localizing to sites of topical photochemotherapy for vitiligo in children: Clinical and dermoscopic findings

“…Hypopigmented PUVA keratosis is another differential, which is photo-induced, but the lesions are elevated papules rather than macules. 3 Although these lesions have been reported before as IGH-like 2 macules, in view of the characteristic dermoscopic features of amoeboid, petaloid, and feathery margins, we opine that these may actually be IGH rather than IGH-like macules. 4 The proposed pathogenesis of IGH is multifactorial and implicates photodamage.…”

“…1,2,6 A subset of both conditions may show some hyperkeratosis, which when significant may result in clinically raised lesions of hypopigmented keratosis, an entity that probably represents the raised hyperkeratotic variant of IGH. 1,3,6 Some patients of both conditions also show epidermal atrophy and flattening of rete ridges. 1,6 Interestingly, the focal or patchy presence of melanin, described by Falabella et al in leucoderma punctata in 1988, is now a known feature of IGH, described as skip areas.…”

A Case of Disseminated Hypopigmented Keratoses Improved with Oral Acitretin

“…In the study reported by Kim et al, 13 cases of HK were reported and 4 of them had a disseminated distribution [ 2 ]. The authors suggested that HK may be a “hyperkeratotic” variant of idiopathic guttate hypomelanosis [ 2 ]. The lesions are distributed more intensively and extensively in our patient compared to previous reported cases.…”

“…A few treatment modalities were tried for the HK in the previous reports including tretinoin, propylene glycol, salicylic acid gel, and cryosurgery without significant improvement [ 1 , 2 ]. One exception is that tretinoin gel and salicylic acid ointment provided marked improvement in the case of the localized HK reported by Kokturk et al [ 3 ].…”

“…Disseminated hypopigmented keratosis (DHK) was first described by Morison et al in 1991 [ 1 ]. No case was reported till the study with the 13 cases of hypopigmented keratosis (HK) was reported by Kim et al in 2013 [ 2 ]. Here we report a case presented with diffuse hypopigmented keratotic lesions considered with the diagnosis of DHK which was improved by oral acitretin and we compared the characteristics of our case with the cases reported before.…”