PA22 Topical tacrolimus management of chronic recurrent skin reaction to mauve stinger jellyfish envenomation

Chronic skin eruptions may follow the acute reaction to envenomation by some jellyfish, the incidence and management of which are not well described. We describe management with topical tacrolimus of a chronic eruption following envenomation by Pelagia noctiluca (‘mauve stinger’), one of the most common stinging jellyfish in the Mediterranean Sea. An 8-year-old girl was stung on the arm by a P. noctiluca in Menorca, Spain. First-aid measures with vinegar and topical antihistamine were administered, and the discomfort settled within 24 h. Five days later, the sting site became increasingly painful and itchy, with superficial ulceration and arm swelling. A second sting site on the lower leg reacted in a similar manner. She was systemically well. She was treated with oral co-amoxiclav, fusidic acid and betamethasone valerate 0.1% cream, and nonadhesive dressings. She initially responded well, but was required to continue the use of potent topical steroid after 3 weeks, as the symptoms recurred within 48 h of halted application. The use of topical tacrolimus cream 0.03% achieved symptom control when used in a slowly weaning regime over 3 months, with a brief flare of skin symptoms around the time of contracting COVID-19. She has now been asymptomatic for 12 months, and the sting site is a maturing scar. Envenomation reactions to jellyfish of the phylum Cnidaria (including P. noctiluca) are the result of varying pathophysiological mechanisms. The tentacles and bell of P. noctiluca carry toxin-releasing epithelial organelles called nematocysts. When triggered, the stinging apparatus fires, injecting thousands of mineralized spine-covered tubules and toxins such as porins [Yanagihara AA, Wilcox C, Smith J, Surrett GW. Cubozoan envenomations: clinical features, pathophysiology and management. In: The Cnidaria, Past, Present and Future (Goffredo S, Dubinsky Z, eds). Cham: Springer, 2016; 637–52]. Acute tissue damage and inflammation are caused by physical trauma and venom effects. Vinegar used at the time of a sting may permanently prevent discharge from unfired and noninjected nematocysts. Hot-water immersion for 30 min inactivates venom, and topical steroids reduce inflammation. The delayed and prolonged skin response (presenting after the primary reaction to envenomation), as in our case, is likely to be an immunological response to the retained, embedded nematocyst structures and may include granulomatous reactions, and eventually scarring. Optimal acute first-