Review of genodermatoses with characteristic histopathology and potential diagnostic delay

The Potential of CRISPR-Guided Therapies in the Dermatology Clinic

Over the past decade, CRISPR has rapidly made its way from the bench to the bedside, providing a newfound therapeutic avenue to not only treat genetic diseases but also permanently cure them. Although there are several clinical trials in early stages, there are so far no CRISPR-based clinical trials for cutaneous disease. In this review, we describe multiple cutaneous diseases that represent ideal targets for CRISPR-based therapeutics owing to known single gene‒causing mutations. We also explore the potential of CRISPR nucleases to treat inflammatory disorders such as eczema and psoriasis, which are not classically categorized as genodermatoses. We describe the therapeutic solutions for these diseases that are guided by various CRISPR-associated (Cas) effector proteins, for example, using Cas9 to permanently edit the DNA of somatic cells, Cas3 to target foreign DNA to combat viral/bacterial skin infections, and Cas13 to edit mutated RNA transcripts in diseases where permanent DNA editing is untenable. Furthermore, we discuss various drug delivery modalities for CRISPR therapeutics, including transdermal patches and microneedles, which are uniquely suited for dermatological diseases. In summary, we highlight the potential of CRISPR-based therapeutics to revolutionize the treatment of cutaneous disease with a goal of being accessible to the practicing dermatologist.

Oral Mucosa and Nails in Genodermatoses: A Diagnostic Challenge

Genodermatoses represent a group of uncommon, hereditary, single-gene skin disorders, characterized by multisystem involvement, heterogeneous clinical manifestations and different degrees of morbidity and mortality. Some genodermatoses may have oral mucosa and nail involvement, since the oral cavity and cutaneous organ system, including nails, share a close embryologic origin. Nail disorders can manifest with nail hypoplasia or nail hypertrophy. Clinical pictures of affected oral mucosa can be extremely heterogeneous, ranging from asymptomatic papules to painful blisters, leukokeratosis, oral papillomas and fibromas to oral potentially malignant disorders and cancerous lesions. Oral mucosa and nails pathological features may occur synchronously or not and are usually associated with other systemic and skin manifestations. In some cases, oral mucosa and nails diseases may be distinct and constitute the principal sign of the genetic disorder, in other cases they represent only a part of the puzzle for the confirmation of the diagnosis. Continued awareness of the correlation between oral mucosa and nails findings can help physicians to diagnose genodermatosis in a timely manner, allowing more effective clinical management and prevention and/or early detection of complications. This article provides an overview of all specific genodermatoses affecting both oral mucosa and nails. Moreover, the correlation between teeth and nails is summarized in tabular form.

Introduction to phacomatoses (neurocutaneous disorders) in childhood

The Dutch ophthalmologist, Jan van der Hoeve, first introduced the terms phakoma/phakomata (from the old Greek word "ϕαχοσ" = lentil, spot, lens-shaped) to define similar retinal lesions recorded in tuberous sclerosis (1920) and in neurofibromatosis (1923). He later applied this concept: (a) to similar lesions in other organs (e.g. brain, heart and kidneys) (1932) and (b) to other disorders (i.e. von Hippel-Lindau disease and Sturge-Weber syndrome) (1933), and coined the term phakomatoses. At the same time, the American neurologist Paul Ivan Yakovlev and psychiatrist Riley H. Guthrie (1931) established the key role of nervous systems and skin manifestations in these conditions and proposed to name them neurocutaneous syndromes (or ectodermoses, to explain the pathogenesis). The Belgian pathologist, Ludo van Bogaert, came to similar conclusions (1935), but used the term neuro-ectodermal dysplasias. In the 1980s, the American paediatric neurologist Manuel R. Gomez introduced the concept of "hamartia/hamartoma" instead of phakoma/phakomata. "Genodermatoses" and "neurocristopathies" were alternative terms still used to define these conditions. Nowadays, however, the most acclaimed terms are "phacomatoses" and "neurocutaneous disorders", which are used interchangeably. Phacomatoses are a heterogeneous group of conditions (mainly) affecting the skin (with congenital pigmentary/vascular abnormalities and/or tumours), the central and peripheral nervous system (with congenital abnormalities and/or tumours) and the eye (with variable abnormalities). Manifestations may involve many other organs or systems including the heart, vessels, lungs, kidneys and bones. Pathogenically, they are explained by interplays between intra- and extra-neuronal signalling pathways encompassing receptor-to-protein and protein-to-protein cascades involving RAS, MAPK/MEK, ERK, mTOR, RHOA, PI3K/AKT, PTEN, GNAQ and GNA11 pathways, which shed light also to phenotypic variability and overlapping. We hereby review the history, classification, genomics, clinical manifestations, diagnostic criteria, surveillance protocols and therapies, in phacomatoses: (1) predisposing to development of tumours (i.e. the neurofibromatoses and allelic/similar disorders and schwannomatosis; tuberous sclerosis complex; Gorlin-Goltz and Lhermitte-Duclos-Cowden syndromes); (2) with vascular malformations (i.e. Sturge-Weber and Klippel-Trenaunay syndromes; megalencephaly/microcephaly-capillary malformation syndromes; CLOVES, Wyburn-Mason and mixed vascular nevus syndromes; blue rubber bleb nevus syndrome; hereditary haemorrhagic telangiectasia); (3) with vascular tumours (von Hippel-Lindau disease; PHACE(S)); (4) with pigmentary/connective tissue mosaicism (incontinentia pigmenti; pigmentary/Ito mosaicism; mTOR-related megalencephaly/focal cortical dysplasia/pigmentary mosaicism; RHOA-related ectodermal dysplasia; neurocutaneous melanocytosis; epidermal/papular spilus/Becker nevi syndromes; PENS and LEOPARD syndromes; encephalocraniocutaneous lipomatosis; lipoid proteinosis); (5) with dermal dysplasia (cerebellotrigeminal dermal dysplasia); and (6) with twin spotting or similar phenomena (phacomatosis pigmentovascularis and pigmentokeratotica; and cutis tricolor).

Genital verruciform xanthoma: lessons from a contemporary multi-institutional series

AIMS

Verruciform xanthoma (VX) is an uncommon lesion, seen in the oral mucosa and rarely occurring at cutaneous genital sites. Reports of exceptional VX presentations dominate the literature; herein, we assess the clinical and histological features of a cohort of routine, consecutive cases.

METHODS AND RESULTS

Clinicopathological features of genital VXs from four academic centres were reviewed. A cohort of 25 lesions from 24 patients (22 male, two female; median age = 62 years), occurred on the scrotum (84%), penis (8%) and perineum/vulva (8%). VX was never suspected clinically; considerations ranged from fibroepithelial polyps to squamous cell carcinoma. Classic diagnostic criteria were present at least focally in each lesion, including verrucous architecture, prominent wedge-shaped parakeratosis extending between exophytic epidermal projections and neutrophils in the stratum corneum. Xanthomatous cells were present in all cases, but scattered to rare in 24%.

CONCLUSIONS

Consecutive genital VXs reliably exhibited classic histopathological features, although the essential finding of xanthomatous cells may be scarce. Our comparison to meta-analyses of published cases found relatively fewer penile and vulvar examples. Additionally, the median age was older than in published series, which have emphasised syndromic associations.