Real-Time Confocal Imaging for Hidradenitis Suppurativa: Description of Morphological Aspects and Focus on the Role of Follicular Ostia

A genome-wide association meta-analysis links hidradenitis suppurativa to common and rare sequence variants causing disruption of the Notch and Wnt/β-catenin signaling pathways

BACKGROUND

The contributions of genetic and environmental risk factors to hidradenitis suppurativa (HS) are both poorly understood.

OBJECTIVE

To identify sequence variants that associate with HS and determine the contribution of environmental risk factors and inflammatory diseases to HS pathogenesis.

METHODS

A genome-wide association meta-analysis of 4814 HS cases (Denmark: 1977; Iceland: 1266; Finland: 800; UK: 569; and US: 202) and 1.2 million controls, searching for sequence variants associated with HS.

RESULTS

We found 8 independent sequence variants associating with HS, 6 common and 2 rare (frequency <1%). Four associations point to candidate causal genes, NCSTN, PSENEN, WNT10A, and TMED10, that all map to the Notch and Wnt/β-catenin signaling pathways, involved in epidermal keratinization.

LIMITATIONS

Limited racial diversity may prevent identification of sequence variants of particular importance in non-Caucasian populations.

CONCLUSIONS

These findings demonstrate that genes and pathways involved in epidermal keratinization are the genetic backbone of HS pathology.

Upregulation of Caveolae-Associated Proteins in Lesional Samples of Hidradenitis Suppurativa: A Case Series Study

Hidradenitis suppurativa (HS) is a chronic, inflammatory skin condition. HS disease management has proven difficult owing to an insufficient understanding of the immunological processes that drive its pathogenesis. We have demonstrated that misregulation of caveolae perturbs inflammatory responses, inhibits cutaneous wound healing, and contributes to immune privilege collapse in other hair follicle-related diseases. However, nothing is known about its role or the role of structural components of caveolae (caveolin [Cav1] 1, Cav2, and Cavin-1) in the pathophysiology of HS. We aimed to identify whether Cav1, Cav2, and Cavin-1 may serve as immunohistochemical markers of HS. Lesional and perilesional HS skin samples from patients (n = 7, mean age = 35.7 years, range = 20-57 years) with active HS and normal skin from control participants (n = 4, mean age = 36.7 years, range = 23-49 years) were used to assess Cav1, Cav2, and Cavin-1 expression and localization by immunofluorescence staining. HS samples demonstrated increased levels of Cav1 compared with normal skin, whereas Cav1, Cav2, and Cavin-1 were all elevated in hair follicles of lesional versus perilesional HS samples, suggesting a potentially novel therapeutic target and highlighting caveolae as potential biomarkers of HS.

The role of imaging technologies in the diagnosis of hidradenitis suppurativa

Hidradenitis suppurativa is a chronic, inflammatory, recurrent, and debilitating disease of the hair follicle. It presents with painful, deep-seated, inflamed lesions, such as nodules, abscesses, sinus tracts, and fistulas, generally located in the main folds. Clinical severity assessment alone can be reductive; noninvasive skin imaging technologies, such as ultrasound, magnetic resonance imaging, medical infrared thermography, computed tomography, and positron emission tomography, provide subclinical anatomical and functional details. These instrumental techniques confirm the clinical suspect, thus allowing an earlier diagnosis and improving patients' clinical evaluation, staging, and management. Finally, they might be helpful for preoperative mapping. In this contribution, we provide an overview of the current knowledge about noninvasive skin imaging techniques with a particular focus on ultrasonography, which is widely used thanks to its precision, versatility, and availability.

Confocal microscopy and optical coherence tomography of inflammatory skin diseases in hairs and pilosebaceous units: A systematic review

Common skin disorders such as acne vulgaris, rosacea and folliculitis are bothersome prevalent inflammatory diseases of hair follicles that can easily be investigated bedside using optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) with micrometre resolution, opening a novel era for high-resolution hair follicle diagnostics and quantitative treatment evaluation. EMBASE, PubMed and Web of Science were searched until 5 January 2023 to identify all studies imaging hair follicle characteristics by RCM and OCT for diagnosis and monitoring of treatment in hair follicle-based skin disorders. This study followed PRISMA guidelines. After inclusion of articles, methodological quality was assessed using the QUADAS-2 critical appraisal checklist. Thirty-nine in vivo studies (33 RCM and 12 OCT studies) were included. The studies focused on acne vulgaris, rosacea, alopecia areata, hidradenitis suppurativa, folliculitis, folliculitis decalvans, lichen planopilaris, discoid lupus erythemasus, frontal fibrosing alopecia and keratosis pilaris. Inter- and perifollicular morphology including number of demodex mites, hyperkeratinization, inflammation and vascular morphology could be assessed by RCM and OCT in all included skin disorders. Methodological study quality was low, and interstudy outcome variability was high. Quality assessment showed high or unclear risk of bias in 36 studies. Both RCM and OCT visualize quantitative features as size, shape, content and abnormalities of hair follicles, and have potential to support clinical diagnosis and evaluate treatment effects. However, larger studies with better methodological quality are needed to implement RCM and OCT directly into clinical practice.

Hidradenitis Suppurativa: morphologic and vascular study of nodular inflammatory lesions by means of optical coherence tomography

BACKGROUND

Hidradenitis Suppurativa (HS) is an inflammatory disease characterized by a recurrent-remission trend and clinical lesions that range from asymptomatic to inflamed, deep-seated nodules with scarring and suppuration.

OBJECTIVE

To identify morphologic and vascular features of HS nodules by means of dynamic optical coherence tomography (D-OCT) and to define if they are correlated to patient endotype and risk of disease progression.

METHODS

A set of standardized clinical pictures and D-OCT images were acquired from 57 inflammatory nodules of 40 patients affected by HS. A set of 20 clinical and D-OCT images were acquired from 20 healthy volunteers as a control group. The comparison of D-OCT features among HS and control group was analyzed. The correlation between HS patient endotype and D-OCT features of the lesions was calculated.

RESULTS

D-OCT enabled to identify vascular and morphological aspects characterizing HS nodular inflammatory lesions. In addition, several D-OCT features were significantly different among distinct disease endotypes.

CONCLUSION

The characterization of HS nodular inflammatory lesions through D-OCT, corresponding to blood vessel dilation and inflammatory associated hyper-vascularization, may have important clinical consequences in the assessment of HS risk of progression, therapeutic decisions and treatment efficacy monitoring.