Marie Baeck

Background: Benzisothiazolinone is a preservative responsible for allergic contact dermatitis, with occupational exposure being a common source of sensitisation. Objectives: To investigate the prevalence of positive patch test reactions to benzisothiazolinone (BIT) in Belgium, between January 2010 and December 2022, and to assess co‐sensitisations to other isothiazolinone derivatives in sensitised patients. Methods: A retrospective monocentric study of patch test results with benzisothiazolinone (BIT) 0.1% petrolatum observed in patients attending a Belgian tertiary hospital. Prevalence, demographic data, concomitant patch test reactions, and clinical relevance were analysed. Results: Overall, 65 of 6128 patients (1.06%) had a positive patch test reaction to benzisothiazolinone, and its sensitisation rate increased from 0.39% in 2010 to 3.72% in 2019 (followed by a decline to 0.71% in 2022). Occupational exposure was relevant in 20% of cases, with painters and metalworkers being the most affected professions. Unexpectedly, 10.8% of BIT‐sensitised patients underwent patch testing due to complications following orthopaedic prosthesis implantation. Conclusions: This study confirms a significant rise in BIT sensitisation over time, followed by a recent unexplained decline. Occupational exposure remains a major risk factor, but other environmental sources, including consumer products, such as leather products, should not be overlooked. The BIT sensitisation in orthopaedic prosthesis‐related complications requires further investigation.

Disseminated granuloma annulare (DGA) is an inflammatory skin disorder characterized by more than 10 erythematous, raised, ring-shaped plaques. Its treatment remains challenging, with conventional therapies showing variable efficacy. We report the case of a woman in her 50s with a 2-year history of DGA refractory to multiple treatments. Given the recent evidence of the role of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway in the granuloma annulare pathophysiology, treatment with upadacitinib 30 mg per day was started with rapid effectiveness and good tolerance. This case underscores the potential of JAK inhibitors as promising therapeutic options for recalcitrant granuloma annulare.

We report a rare life‐threatening presentation of postsurgical pyoderma gangrenosum (PG) after augmentation mammoplasty in a 32‐year‐old woman. Six days after surgery, the patient presented with fever and erythema at surgical wounds. In view of a suspected postsurgical infection, the patient was first treated with antibiotics and removal of breast protheses. In spite of this treatment, in a few days the patient developed a state of shock with multiorgan failure. The antibiotic coverage was broadened several times and multiple extensive surgical debridement with resection of the mammary glands were performed but did not improve the clinical situation. Twelve days after admission, the diagnosis of PG with systemic features was suspected and clinical improvement was observed within 24 h of methylprednisolone administration. PG can mimic the cutaneous and systemic features of necrotizing wound infection of surgical site. Biopsy and culture are critical to differentiating necrotizing neutrophilic dermatosis from necrotizing infection. The diagnosis of this less common form of PG is challenging and this case highlights how the frequent misdiagnosis with infection may result in ineffective antibiotic treatment and how the unnecessary surgical debridement may prolong and exacerbate the condition.

Introduction The efficacy of conventional treatments for alopecia areata (AA) has been extremely variable and disappointing, with a high rate of relapse. Recent clinical trials and real-life studies have demonstrated efficacy and safety of baricitinib (an oral Janus kinase 1 and 2 inhibitor) in alopecia areata. Methods We retrospectively evaluated the effectiveness and tolerance of baricitinib in alopecia areata in a real-life Belgian monocentric adult cohort. The primary outcome was evaluated by the percentage of patients who achieved a Severity of Alopecia Tool (SALT) score of ≤ 20 at the end of the follow-up. All treatment-emergent adverse events were collected. Results In this 19-patient series, with a median ± interquartile range (IQR) follow-up duration of 13 ± 16.2 months, we demonstrated that: (i) hair regrowth was observed in nearly 90% of patients between 4 and 16 weeks after initiation of baricitinib; (ii) at the end of the follow-up, more than 70% and, in particular, 100% of patients with patchy AA, reached the primary outcome (SALT score ≤ 20); (iii) almost half of the patients, mostly with patchy AA, showed a complete hair regrowth (SALT score = 0), within a median ± IQR treatment time of 8.5 ± 10 months; (iv) baricitinib was discontinued in three patients with total hair regrowth, two of whom relapsed; and (v) no serious adverse events were reported. Conclusion Baricitinib is effective in treating patients with alopecia areata, particularly for the patchy phenotype, but with a risk of relapse after discontinuation. Safety data are reassuring, with lipid changes being the most frequent adverse event.