Severe mosquito bite allergy complicated by bacterial infection in a 7-year-old child: a case report and brief review of the literature.

Introduction: SMBA is a cutaneous form of CAEBV that predominantly affects adolescents and children from East Asian countries. It is characterized by local skin erythema, bullae, ulcers, necrosis, and scarring following a mosquito bite. Affected patients may experience IM-like systemic inflammatory reactions. SMBA mainly involves NK cells and has the potential to progress to NK/T-cell lymphoma or invasive NK-cell leukemia.

Case report: A 7-year-old female was admitted to the hospital owing to recurring fever, skin allergies, and multifocal severe ulcerative necrotic skin lesions affecting both lower limbs. The authors primarily suspected bacterial infection, and debridement was insufficient to manage it. Pathological examination of residual skin tissues around the necrotic lesion revealed EBER-positive T cells. Eventually, the patient was diagnosed with SMBA complicated by bacterial infection based on diagnostic criteria and pathology findings. The patient responded well to timely antiviral and antibacterial treatment, with no deterioration during regular follow-up visits.

Conclusions: SMBA is a subtype of CAEBV that is characterized by severe skin ulceration and is easily missed or misdiagnosed. Based on its mosquito bite history, pathological characteristics, and laboratory indicators, SMBA could expand new diagnostic and therapeutic approaches to the ulcerative skin diseases.