Annular epidermolytic ichthyosis: a case report and literature review☆☆☆

Annular epidermolytic ichthyosis is a rare subtype of epidermolytic ichthyosis that is characterized by erythematous, polycyclic, and migratory scaly plaques accompanied by palmoplantar keratoderma. This report presents the case of an 8-year-old girl who developed migratory, erythematous, scaly plaques associated with palmoplantar keratoderma. The initial hypothesis was erythrokeratodermia variabilis et progressiva; however, the finding of epidermolytic hyperkeratosis in histopathological examination led to the diagnosis of annular epidermolytic ichthyosis.


Introduction
Annular epidermolytic ichthyosis (AEI) is a rare phenotypic variant of epidermolytic ichthyosis (EI), also known as congenital bullous ichthyosiform erythroderma, an autosomal plaques with prominent borders, affecting the mesogastrium, cubital fossae, popliteal fossae, and inguinal and cervical regions, as well as palmoplantar hyperkeratosis and yellowish hyperkeratotic plaques on the scalp and nasal introitus (Figs. 1, 2 and 3A). No associated changes in hair, nails, or mucosa were observed.
The patient denied any symptoms and there was no background of family history of similar cases and consanguinity. After one month, she was reassessed and the appearance of the plaques changed, increasing the extension of the affected areas; however, the polycyclic aspect disappeared (Fig. 3B).
Skin biopsy in the extensor portion of the forearm showed acanthosis, papillomatosis, and hyperkeratosis with marked epidermolysis in the granular layer (Fig. 4).

Discussion
AEI was first described in 1992 by Sahn et al. 5 and is the result of dominant mutations in the keratin 1 and keratin 10 genes. 1---7 Individuals with this variant may present with bullous ichthyosis at birth and hyperkeratotic lichen plaques on the areas of flexion and extensor surfaces in the first years of life. 1 Characteristically, they also develop recur-

Figure 2
Erythematous, hyperkeratotic plaque, with prominent and geographical border in the cervical region. Yellowish keratotic plaques at the angle of the mouth and chin. rent outbreaks of annular, polycyclic, erythematous, and scaly plaques on the trunk and proximal extremities. 1,4 The present authors have reviewed the literature published in English, Portuguese, and Spanish since its description and found 19 cases in 10 publications that are summarized in table 1. 1---10 In the histopathology, the hyperkeratotic lesions of the AEI revealed hyperkeratosis, acanthosis, and a thickened granular layer. Keratinocytes in the spinous layers and superior granulosa of the epidermis demonstrated cytoplasmic vacuolization and prominent keratohyaline granules. 1,2,4,6 Basal keratinocytes appeared normal, but there was an increase in the number of mitoses. Regarding findings from electron microscopy, there were abnormal keratin filaments in the suprabasal keratinocytes, increase of kerato-hyaline  Unreported. Oral isotretinoin, topical glucocorticoids, and keratolytics. Topical tazarotene with partial response. granules in granule layer cells, and perinuclear accumulations of thickened tonofilament that formed an interrupted perinuclear ring. 4,5 The main differential diagnosis of annular epidermolytic ichthyosis is with erythrokeratodermia variabilis et progressiva (EKVP), 1,2 an autosomal dominant cutaneous disorder characterized by erythrokeratodermia and migratory erythematous plaques. 1,2,7 EKVP is typically associated with mutations in the connexins 30.3, 31, and 43 (GBJ4, GJB3, and GJA1), but recent studies suggest genetic heterogeneity. Distinctive features of EKVP include onset during childhood, absence of epidermal fragility, and histology without evidence of epidermolysis. 1 The major ultrastructural feature of EKVP is a reduction in the number of keratinosomes in the granular layer. 2 Treatment options in the small number of patients reported included topical medications such as retinoids, topical corticosteroids, propylene glycol, calcipotriene, and keratolytic agents, and little response was observed. 5,8,9,10 Three articles report good response with systemic retinoids; two articles cite acitretin treatment with good response 6,8 and another reports good response with low doses of isotretinoin. 7

Financial support
None declared.

Authors' contributions
Emanuella Stella Mikilita: Approval of final version of the manuscript; conception and planning of the study; drafting and editing of the manuscript.
Irina Paipilla Hernandez: Approval of final version of the manuscript; conception and planning of the study; draft- ing and editing of the manuscript; collection, analysis, and interpretation of data; critical review of the literature.
Ana Letícia Boff: Drafting and editing of the manuscript; collection, analysis, and interpretation of data.
Ana Elisa Kiszewski: Approval of final version of the manuscript; conception and planning of the study; drafting and editing of the manuscript; collection, analysis, and interpretation of data; intellectual participation in the propaedeutic and/or therapeutic conduct of the studied cases; critical review of the literature; critical review of the manuscript.

Conflicts of interest
None declared.