Histologic Patterns and Clues to Autoinflammatory Diseases in Children: What a Cutaneous Biopsy Can Tell Us

Autoinflammatory Keratinization Diseases-The Concept, Pathophysiology, and Clinical Implications

Recent advances in medical genetics elucidated the background of diseases characterized by superficial dermal and epidermal inflammation with resultant aberrant keratosis. This led to introducing the term autoinflammatory keratinization diseases encompassing entities in which monogenic mutations cause spontaneous activation of the innate immunity and subsequent disruption of the keratinization process. Originally, autoinflammatory keratinization diseases were attributed to pathogenic variants of CARD14 (generalized pustular psoriasis with concomitant psoriasis vulgaris, palmoplantar pustulosis, type V pityriasis rubra pilaris), IL36RN (generalized pustular psoriasis without concomitant psoriasis vulgaris, impetigo herpetiformis, acrodermatitis continua of Hallopeau), NLRP1 (familial forms of keratosis lichenoides chronica), and genes of the mevalonate pathway, i.e., MVK, PMVK, MVD, and FDPS (porokeratosis). Since then, endotypes underlying novel entities matching the concept of autoinflammatory keratinization diseases have been discovered (mutations of JAK1, POMP, and EGFR). This review describes the concept and pathophysiology of autoinflammatory keratinization diseases and outlines the characteristic clinical features of the associated entities. Furthermore, a novel term for NLRP1-associated autoinflammatory disease with epithelial dyskeratosis (NADED) describing the spectrum of autoinflammatory keratinization diseases secondary to NLRP1 mutations is proposed.

Systemic autoinflammatory disorders

Inflammation is a physiologic defense mechanism against an out-side attack. Usually, it resolves after the removal of noxious causes, but systemic autoinflammatory disorders (SAIDs) have recurrent or repeated acute inflammation through uncontrolled gene function, which can present as gain-of-function or loss-of-function of a gene during inflammation. Most SAIDs are hereditary autoinflammatory diseases and develop by dysregulation of innate immunity through various pathways including inflammasomes, endoplasmic reticulum stress, nuclear factor-κB dysregulation, and interferon production. The clinical manifestations include periodic fever with various skin findings such as neutrophilic urticarial dermatosis, or vasculitic lesions. Some SAID cases stem from immunodeficiency or allergic reactions related to monogenic mutation. The diagnosis of SAIDs is based on clinical findings of systemic inflammation and genetic confirmation, and have to exclude infections or malignancies. Moreover, a genetic study is essential for clinical features to be suspect SAID with or without a family history. Treatment is based on understanding the immunopathology of SAID, and targeted therapy to control disease flares, reduce recurrent acute phases and prevent serious complications. Diagnosing and treating SAID requires understanding its comprehensive clinical features and pathogenesis related to genetic mutation.

COVID-associated non-vasculitic thrombotic retiform purpura of the face and extremities: A case report

SARS-CoV-2 infection can manifest many rashes. However, thrombotic retiform purpura rarely occurs during COVID-19 illness. Aggressive anti-COVID-19 therapy with a high-dose steroid regimen led to rapid recovery. This immunothrombotic phenomenon likely represents a poor type 1 interferon response and complement activation on the endothelial surface in response to acute infection.