CPC03 Notch your average dermatitis

We present the case of triangular nasal notch sign in a White woman with previous exposure to tumour necrosis factor (TNF) inhibition for Crohn disease, which persisted throughout a biologic-free period. The 33-year-old woman presented with symptoms of nasal rash, itch and cosmetic concern for bilateral indentations in the nasal soft triangle, ongoing for 6 years. Medical history was notable for childhood atopic dermatitis, herpes labialis and Crohn disease. Her Crohn disease was well controlled on ustekinumab, commenced in the last year. She commenced adalimumab 6 years before the rash first appeared, but had discontinued this agent 4 years prior to her presentation to dermatology. On examination she had patchy erythema with scale and crust affecting her nasal tip, septum, alar sidewalls and columella, with loss of the normal nostril contour and cicatricial indentation at the apex of the nasal soft triangle bilaterally. She had evidence of acute herpes simplex virus (HSV)-1 infection of the upper lip. A punch biopsy from the left nasal tip showed acanthosis and spongiosis with a dermal mixed inflammatory infiltrate including lymphocytes, histiocytes and neutrophils. There was focal ulceration and intraepithelial small abscesses, without features of granulomatous inflammation. Triangular nasal notch sign is a clinical sign that was first described in 2019 (Mesnard C, Aubert H, Bourreille A et al. The triangular nasal notch sign in patients with Crohn disease treated with tumour necrosis factor inhibitors. Br J Dermatol 2019; 181: 1103–4). This group reported eight patients with Crohn disease exposed to TNF inhibitors, presenting with a cicatricial triangular nasal notch, and hypothesized that TNF inhibition specifically was implicated in the development of the phenomenon. Similarly to these patients, our case had exposure to anti-TNF; however, the persistence of nasal dermatitis throughout a ‘biologic-free’ period is novel. The pathophysiology of TNF inhibitor-induced nasal dermatitis and triangular nasal notch sign is not fully understood. It has been hypothesized that it is within the scope of paradoxical reactions seen with TNF inhibitors and persistent Staphylococcal aureus infection. An association with HSV-1 has not been previously reported in the context of this condition. Nasal swabs in this case showed commensals only; however, clinical improvement of nasal inflammation was achieved with topical mupirocin, prophylactic valaciclovir and a short course of oral azithromycin. The singular association with Crohn disease and limited involvement of the nose is also as yet unexplained and requires further research. We encourage greater reporting of this phenomenon, to increase awareness among clinicians and to help identify the exact pathomechanism and optimal treatment.