Unveiling idiopathic guttate hypomelanosis: pathology, immunohistochemistry, and ultrastructural study

Abstract

Background Idiopathic guttate hypomelanosis (IGH) is a pigment disorder of unknown etiology. Despite its high prevalence and the unaesthetic appearance of the lesions, there are relatively few histological studies on this disorder. This is an important gap to understanding its pathogenesis.Objectives To assess the microscopic structure of IGH lesions compared to normal adjacent skin areas and the possible interaction between melanocytes and the subjacent dermis. MethodsIn this cross-sectional study, we took biopsy specimens of hypochromic lesions and adjacent normal skin from 20 patients with IGH. We analyzed the fragments using routine stains, immunohistochemistry, and electron microscopy. ResultsWe found superficial dermal fibrosis in 90% (18/20) of our IGH cases and unreported keratinocyte cytoplasmic changes on electron microscopy. ConclusionOur results suggest an interaction between melanocytes and the subjacent dermis in IGH. These findings can help to understand melanocyte biology and the pathogenesis of other achromic lesions.

Efficacy and Safety of 5-Fluorouracil Tattooing to Repigment Idiopathic Guttate Hypomelanosis: A Split-Body Randomized Trial

“…This split-body, single-blinded trial was conducted in August 2016 to December 2019 at a private dermatology We included adults (30-70 years) with Fitzpatrick skin Types II to V diagnosed with IGH 5 with symmetrically distributed lesions in their upper or lower limbs. Main exclusion criteria were pregnancy, breastfeeding, diabetes, coagulation or collagen disorders, fragile or sensitive skin, history of keloids, poor wound healing, immunosuppression and vitiligo.…”

“…4 Histopathological findings include decreased melanin pigment, reduced number of melanocytes, and superficial dermal fibrosis. 5 The main treatments include topical medications (phenol, 6 tacrolimus, 7 and pimecrolimus 8 ) and surgical procedures (cryotherapy, 9 nonablative fractional laser, 10 and CO 2 fractional laser 11 ). Repigmentation of achromic scars can occur after surgical removal of dermal fibrosis 12 or drug delivery of antifibrotic agents.…”

“…13 We hypothesized that the reduction or elimination of subjacent dermal fibrosis could repigment IGH lesions. 5 5-fluorouracil (5FU), an effective antifibrotic agent 14 that stimulates melanin spread and melanocyte migration and proliferation, 15 can be safely injected into achromic and hypertrophic lesions using microneedling techniques. 13,16 In 2018, we obtained good results treating IGH with 5FU delivery using a tattoo equipment.…”