Annular epidermolytic ichthyosis: An exceptional mild subtype of epidermolytic ichthyosis without genotype and phenotype correlation

Visualization of Keratin with Diffuse Reflectance and Autofluorescence Imaging and Nonlinear Optical Microscopy in a Rare Keratinopathic Ichthyosis

“…Sequencing of KRT1 gene revealed a heterozygous missense mutation c.1436T > C in the proband, designated as p.Ile479Thr, which leads to a change of isoleucine to threonine in the highly conserved 2B domain of keratin 1 ( Figure 3 ). This particular mutation has been described in a few cases of annular epidermolytic ichthyosis (AEI, OMIM: 607602) and in the background of the major form of EI (OMIM: 113800), resulting in distinct phenotypes [ 15 , 16 ]. Genetic tests from the parents did not identify this pathogenic variant.…”

“…However, c.1436T > C has been described to cause both severe and mild EI phenotypes including AEI (OMIM: 607602). Although EI subtypes are similar at birth with blistering and erosions, the subsequent symptoms of AEI and major EI types are different, with AEI resulting in a milder phenotype [ 16 ]. Our patient did not show characteristics of AEI, namely, recurrent flares of annular erythematous lesions with periods of almost clear skin, yet cutaneous symptoms with relapses and remissions were seen.…”

“…However, our case supports the notion that for skin symptoms, such as hyperkeratosis, blistering, erythema, and the severity of the disease, the correlation is loose. The loose genotype–phenotype correlation is hypothesized to be due to yet unidentified genetic and epigenetic factors [ 16 ]. Although the diagnosis of ichthyoses is based on genetical testing, conventional histology is often used preceding genetical analysis or in cases when a genetical background cannot be identified.…”

Newborn Girl Presenting With Erythema and Blisters

“…AEI is a milder phenotype of epidermolytic ichthyosis (EI) caused by KRT1 and KRT10, which are expressed in suprabasal keratinocytes and maintain cytoskeletal stability and skin barrier function. 3 Keratin variations result in increased transepidermal water loss and inflammation on exposure to noxious environmental factors. 4 Typical features of AEI include superficial erosions, vesicles and bullae with or without erythema early on, and recurrent migratory annular and polycyclic erythematous plaques on the trunk and extremities.…”

“…5 Palmoplantar keratoderma (PPK) is associated with KRT1 variations, rather than those of KRT10. 2,3 Original magnification ×50 During the intermittent period, all lesions, excluding PPK in patients with KRT1 variations, demonstrate near-complete resolution, distinguishing AEI from the major EI forms. 3 AEI's histopathology is characterized by epidermolytic hyperkeratosis.…”