Hypersensitivity to mosquito bites (HMB) is a rare disease characterized by intense local skin reactions with general symptoms, such as high fever and regional lymphadenopathy after mosquito bites. Epstein–Barr virus (EBV) chronic infection and NK cell lymphoproliferative disease have been reported first in diagnosed HMB patients. Here, we present the case of a 6-year-old girl with 2 months’ history of bullae and necrotic skin lesions, accompanied by a high temperature, visual hallucinations, and liver dysfunction after mosquito bites. A histopathologic examination of the skin lesion showed vasculitis and EBV infection. We could not detect any findings of hematologic malignancies or NK cell proliferative disease in the patient. Clinicians should closely evaluate HMB patients for possible development of lymphoproliferative status or hematologic malignant disorders.