October 2025. Volume 34.

Dermatology Snapshots

In this edition:

  • Treatment algorithms for androgenetic alopecia

  • Is MTX drug survival increased with SC MTX vs Oral?

  • What are the main skin features of Still’s Disease?

  • GLP-1 receptor agonists and hair loss

  • Metformin and doxycycline for HS: an RCT

  • Identifying patients at high risk of myeloproliferative disorders in aquagenic pruritus

A Canadian Consensus on Androgenetic Alopecia: Approach and Management

Landells et al., J Cutaneous Med Surg 2025

Why we chose this paper?

This is the first pan-Canadian expert consensus on AGA, produced by a multidisciplinary panel using a modified Delphi process. It fills a practical gap for clinicians by synthesising available evidence and local practice patterns into treatment algorithms, and is relatively aligned with UK practice.

Study aim and design

The authors performed a systematic literature review (2003–2023, extended to 25 years for pivotal trials), rated evidence (Oxford levels) and ran a 3-round modified Delphi (11 panellists: 9 dermatologists, 1 family physician, 1 plastic surgeon). Interventions (n=40) were voted on for recommendation, and male/female treatment algorithms were produced.

What were the main findings?

  • Consensus (≥75%) to recommend: oral dutasteride, oral finasteride, oral minoxidil, topical minoxidil, PRP, topical finasteride, microneedling.

  • Near-consensus (55–74%): ketoconazole shampoo, LLLT, aminexil as adjuncts.

  • Not recommended: 17 interventions (e.g., amla syrup, microfilament threads, many nutraceuticals).

  • Algorithms: first-/second-/third-line options stratified by sex and menopausal status; topical/oral combinations and mechanism-based pairing encouraged. SEE BELOW

Limitations and applicability

  • Delphi = expert opinion: results depend on panel composition and threshold choices; evidence tables were summarised rather than critically appraised in full.

  • Potential bias: industry funding (unrestricted grant noted) and involvement of cosmetically affiliated authors may influence practice pragmatics.

  • Evidence gaps: many recommendations (e.g., PRP, microneedling, topical finasteride) rest on heterogeneous, small RCTs or observational data; concordant with international guidance in recommending minoxidil/5-ARIs but stronger, high-quality RCTs are still needed.

What’s the take home message?

This pragmatic consensus supports established first-line medical therapy (minoxidil, oral 5-ARIs) and recognises emerging adjuncts (PRP, microneedling, topical finasteride). Use the algorithms as a practical framework, but individualise care and counsel patients about variable evidence strength and safety.

Impact of Methotrexate Administration Route on Drug Survival in Psoriasis: Results from PSOBIOTEQ

Paris C, Curmin R, Gouillon L, et al. J Eur Acad Dermatol Venereol. 2025;00:1–9. doi:10.1111/jdv.70044

Why we chose this paper

Methotrexate (MTX) remains a first-line systemic treatment for moderate-to-severe psoriasis worldwide, but real-world data comparing oral (PO) versus subcutaneous (SC) routes are limited. This French multicentre cohort analysis provides practical insights into whether administration route influences long-term drug survival and tolerability—critical questions for optimizing cost-effective psoriasis care in the biologic era.

Study aim and design

This was a prospective, real-world cohort study from the Psobioteq registry (2012–2023), including 406 MTX-naïve psoriasis patients starting monotherapy (58% PO, 42% SC). Kaplan–Meier and multivariate Cox regression analyses assessed drug survival and reasons for discontinuation, with adjustment for demographic and clinical variables.

What were the main findings?

  • Overall MTX survival: no significant difference between oral and subcutaneous routes (p = 0.15).

  • One-year survival: 70% (SC) vs. 66% (PO); two-year survival: 60% (SC) vs. 42% (PO).

  • Discontinuation causes:

    • Lack of effectiveness more frequent with oral MTX (62% vs. 50%).

    • Intolerance higher with subcutaneous MTX (40% vs. 18%).

  • Predictors: onychopathy increased discontinuation risk (HR 1.57), age ≥ 65 years improved survival (HR 0.54).

  • Dosing variability: oral MTX required more adjustments (52% vs. 44%) and route switches (29% vs. 6%).

Limitations and applicability

The study’s strengths lie in its prospective, multicentre real-world design and 10-year dataset. However, the modest sample (n = 406) limits power, and residual confounding cannot be excluded due to its observational nature. Findings align partly with rheumatoid arthritis data suggesting improved efficacy with SC administration but differ regarding intolerance, possibly reflecting population-specific tolerability or reporting bias. Applicability is high for clinicians weighing route choice before biologics, especially where MTX cost advantages remain relevant.

What’s the take home message?

While methotrexate’s overall durability is similar across routes, subcutaneous MTX may reduce inefficacy-related discontinuation but increase intolerance. Oral MTX remains a reasonable first-line option, but clinicians may consider SC initiation for poor responders—monitoring closely for side effects.

Unfolding Dermatological Spectrum of Still’s Disease: A Cohort Study from the International AIDA Network Still’s Disease Registry

Calabrese L, D’Onghia M, Cartocci A, et al. Rheumatology (Oxford). 2025;64(2):1–14. doi:10.1093/rheumatology/keae215

Why we chose this paper

Still’s disease can present with a wide range of cutaneous manifestations, many of which are atypical and can lead to diagnostic delay. This large, international registry study (n=518) offers one of the most comprehensive analyses to date of dermatological findings in Still’s disease, highlighting clinical patterns across age and ethnicity. For dermatologists, these insights are invaluable in recognising early systemic disease.

Study aim and design

The authors retrospectively analysed data from the AIDA Network Registry, assessing the prevalence and types of cutaneous lesions in Still’s disease and their correlations with ethnicity, age of onset, disease course, and severity scores (Pouchot and Rau). Both adult-onset (AOSD) and juvenile (sJIA) cases were included.

What were the main findings?

  • 63.9% of patients had the classic salmon-coloured evanescent rash.

  • 21.2% had atypical skin lesions, including macules (7.7%), urticarial eruptions (5.9%), erythema (5.2%), and persistent pruritic papules/plaques (PPPP; 4.8%).

  • Hispanic patients showed significantly more atypical lesions, particularly macules and PPPP, compared to White and Arab groups.

  • The typical rash correlated with higher systemic disease activity (Pouchot ≥7; p<0.001).

  • No link was found between skin findings and macrophage activation syndrome (MAS).

Limitations and applicability

The retrospective design and incomplete data capture limit causal interpretation. Ethnicity-based analyses are intriguing but need genetic validation. Nonetheless, this study’s global scale and inclusion of diverse populations strengthen its external validity. For practising dermatologists, the findings underscore the diagnostic relevance of recognising atypical rashes—especially in non-White patients or older adults.

What’s the take home message?

Still’s disease skin manifestations are heterogeneous and ethnicity-dependent. Recognising both classic and atypical lesions is essential for timely diagnosis and management of this potentially life-threatening systemic disease.

Glucagon-like peptide-1 receptor agonists and hair loss: An emerging clinical concern

Paris C, Curmin R, Gouillon L, et al. J Eur Acad Dermatol Venereol. 2025;00:1–9. doi:10.1111/jdv.70044

Why we chose this paper

With GLP-1 receptor agonists (GLP-1RAs) such as semaglutide and tirzepatide now widely prescribed for diabetes and weight management, reports of drug-associated hair loss have grown rapidly on social media and in clinical practice. This short communication brings together pharmacovigilance and clinical data, providing a timely overview for dermatologists increasingly asked about this potential adverse effect.

Study aim and design

This was a narrative review and evidence summary compiling regulatory safety alerts, adverse-event database analyses, retrospective cohorts, and clinical trials (n≈8,847). The authors synthesised findings on alopecia incidence, risk factors, and biological plausibility across GLP-1RA agents.

What were the main findings?

  • FDA pharmacovigilance signal (2023): hair loss flagged for semaglutide, liraglutide, dulaglutide, exenatide, and tirzepatide.

  • FAERS disproportionality analysis: elevated reporting odds for semaglutide (ROR 2.46) and tirzepatide (ROR 1.73).

  • Retrospective cohort (Burke et al.): 12.4% of users developed alopecia—mostly androgenetic (7.7%) or telogen effluvium (4.1%).

  • Randomised data (Moll et al.): pooled relative risk 5.67; estimated 57/1000 incidence over 2 years.

  • Possible mechanisms: rapid weight loss–induced telogen effluvium, micronutrient deficiencies (iron, zinc, biotin), and thyroid-axis disruption.

  • Dose and route matter: oral semaglutide linked to higher rates than subcutaneous formulations.

Limitations and applicability

Most datasets were observational or derived from spontaneous reports by non-dermatologists, risking misclassification of alopecia type. Confounding from weight loss itself remains unresolved. No causality has been established. Still, consistency across datasets strengthens the signal. Compared with prior data on post-bariatric telogen effluvium, incidence appears somewhat higher, hinting at a drug-specific component. Dermatologists should remain alert as GLP-1RA use expands into metabolic and inflammatory dermatoses.

What’s the take home message?

Hair loss may be an under-recognised adverse effect of GLP-1RAs, particularly semaglutide and tirzepatide. Clinicians should ask about hair changes, screen for nutritional deficiencies, and report cases to build the evidence base.

Metformin in conjunction with doxycycline is not superior to doxycycline monotherapy for hidradenitis suppurativa: Results of a phase III double-blinded randomized placebo-controlled trial

Aarts P, Koerts NDK, van Huijstee JC, et al. Br J Dermatol. 2025;00:1–2. doi:10.1093/bjd/ljaf361

Why we chose this paper

Metformin has gained interest as a potential adjunctive therapy for hidradenitis suppurativa (HS) because of its anti-inflammatory and insulin-sensitising effects, yet robust randomized data were lacking. This is the first phase III double-blind RCT to assess whether adding metformin to doxycycline improves HS outcomes, addressing a clinically relevant question for dermatologists managing mild-to-moderate disease.

Study aim and design

A multicentre, double-blind, placebo-controlled trial (NCT04649502) enrolled 62 patients with mild-to-moderate HS across three Dutch university centres. Participants received metformin (500–1500 mg/day) + doxycycline (100 mg/day)or placebo + doxycycline for 24 weeks.
Primary endpoint: change in IHS4 (International Hidradenitis Suppurativa Severity Score).
Secondary endpoints: IHS4-55, HiSCR50, abscess/nodule (AN) count, quality of life (DLQI), flares, pain, and metabolic parameters.

What were the main findings?

  • Both groups showed significant IHS4 improvement, but no difference between them (P = 0.596).

  • No between-group differences in HiSCR50, IHS4-55, AN count, DLQI, or pain.

  • Metformin + doxycycline achieved greater metabolic improvements: BMI ↓ (P < 0.001), waist circumference ↓ (P = 0.006), fasting glucose ↓ (P = 0.049).

  • Mild side effects; overall treatment well tolerated.

  • Both groups showed a strong doxycycline response, suggesting possible ceiling effect in mild disease.

Limitations and applicability

While well designed and powered, the study’s short duration (24 weeks) and focus on mild-to-moderate HS may underestimate longer-term metabolic benefits. The authors note prior metformin studies were largely open-label or retrospective; thus, this RCT tempers earlier optimism.
Metformin’s metabolic benefits—weight, glucose, insulin resistance—remain relevant for patients with HS and metabolic syndrome, even if not directly anti-inflammatory in the short term.

What’s the take home message?

In mild-to-moderate HS, adding metformin to doxycycline does not enhance short-term clinical outcomes, though metabolic improvements support its role in managing HS comorbidities.

SHORTS

Witte F. et al. Aquagenic Pruritus Questionnaire: Predicting Myeloproliferative Neoplasms in Patients with Aquagenic Pruritus

Multicentre German group presents the first validated patient-reported outcome measure for aquagenic pruritus (AP). After iterative item reduction in 229 subjects, a four-question tool emerged: water-provoked itch, duration >30 min, abdominal localisation and heat as co-trigger. Score <10 points indicates high likelihood of underlying myeloproliferative neoplasm (MPN). Final validation cohort: 76 AP patients (37 with MPN) plus 76 non-aquagenic chronic pruritus controls; performance 97 % sensitivity, 80 % specificity, +LR 4.8, –LR 0.03. Retrospective analysis correctly predicted five patients who developed polycythaemia vera 2–5 years before haematological changes. Higher leukocyte, erythrocyte and platelet counts correlate with low APQ scores. Test–retest reliability excellent (κ>0.9); completion <2 min, no extra equipment. Consultant dermatologists should embed APQ in routine work-up of water-induced itch on normal skin: score <10 mandates full blood count, JAK-2 V617F mutation and urgent haematology referral.

Add the four numbers in the table below:

  • Total < 10 → high MPN risk → organise FBC, JAK-2, haematology referral.

  • Total ≥ 10 → MPN unlikely → continue standard AP care.

(Low score = high suspicion; high score = low suspicion.)

Question Answer worth 0 pts Answer worth 3 pts Rationale
1. Itch on water contact? Yes No MPN patients always itch with water → 0 pts
2. Duration after water? > 30 min ≤ 30 min MPN itch lingers → longer = 0 pts
3. Abdomen involved? Yes No MPN itch often localises here → 0 pts
4. Heat also triggers? Yes No MPN patients commonly report heat → 0 pts