Abstract: This article reports a 14-year-old boy who presented with "a nearly 7-year history of a right upper arm mass and a more than 1-year history of cervical lymphadenopathy". His main clinical manifestations included a subcutaneous mass in the right upper arm, bilateral eyelid and submandibular masses, and multiple enlarged cervical lymph nodes, accompanied by persistent peripheral blood eosinophilia. Biopsies of the right upper arm lesion and a left submandibular lymph node showed lymphoid hyperplasia with prominent eosinophilic infiltration, vascular and fibrous tissue proliferation, and eosinophilic microabscess formation in the left submandibular lymph node, confirming the diagnosis of Kimura′s disease. The lesions regressed markedly after glucocorticoid therapy but recurred after treatment discontinuation. Because the patient and his family were concerned about long-term glucocorticoid therapy, mepolizumab was subsequently administered. Peripheral eosinophil counts normalized, whereas the local tissue lesions showed limited improvement. A multidisciplinary team comprehensively evaluated the diagnosis, the need for repeat biopsy of atypical lymph nodes on imaging, the possible association between the cardiac valve abnormalities and the underlying disease, and subsequent treatment options. The patient is currently receiving methotrexate with folic acid supplementation and remains under regular follow-up. This case indicates that the diagnosis of Kimura′s disease relies on clinical manifestations and histopathological findings. Once diagnosed, comprehensive evaluation, individualized treatment, and long-term management should be implemented.