D1.15 - True Mugwort Sensitization Presenting as Severe Atopic Dermatitis: A Diagnostic Challenge

A 64-year-old male was referred for evaluation of chronic recurrent skin lesions accompanied by severe pruritus and persistent hyperuricemia. The cutaneous manifestations had been present for over one year and demonstrated a relapsing–remitting course with partial, short-term response to systemic corticosteroids. The most severe exacerbation occurred in August 2025 after prolonged gardening and exposure to weeds.

Given the clinical suspicion of allergic or histamine-mediated disease, the patient attempted dietary avoidance of histamine-rich foods without clinical benefit. Regular use of emollients resulted in only minimal improvement. Comprehensive allergy assessment, including ALEX-2 multiplex testing, revealed sensitization to rArtv1 (mugwort allergen).

Further allergological work-up performed in September 2025 included complete blood count, total IgE, liver function tests, serum tryptase, and skin biopsy with histopathological examination. Laboratory findings showed markedly elevated total IgE levels (690 IU/mL) with normal serum tryptase (5 ng/mL), excluding mast cell activation disorders. Serum uric acid was significantly increased (640 µmol/L). Histopathological examination demonstrated epidermal hyperplasia, spongiosis, intercellular edema of the interfollicular epidermis, and features consistent with secondary bacterial infection.

Based on the clinical presentation, allergological evaluation, and histopathological findings, a diagnosis of true sensitization to mugwort pollen with clinical manifestation as severe atopic dermatitis (SCORAD 58) was established.

A multidisciplinary therapeutic approach was initiated on October 6, 2025, including chlorinated baths for 10 days, intensive emollient therapy, methotrexate 15 mg weekly with folic acid supplementation, febuxostat 80 mg daily, and short-term systemic corticosteroid therapy (methylprednisolone 8 mg daily with gradual tapering).

Marked clinical improvement was observed by December 2025, with significant regression of skin lesions (Images added). The patient remains on methotrexate, folic acid, febuxostat, and regular use of topical emollients to achieve and maintain sustained remission.

This case highlights the complexity of diagnosing severe atopic dermatitis associated with true aeroallergen sensitization and elevated total IgE, emphasizing the importance of comprehensive allergological assessment and a multidisciplinary treatment strategy. The patient has consented to the publication of this case and its photo.