Recently, a 50-year-old middle-aged male patient was admitted to our hospital with a painless subcutaneous nodule in the neck. What is Kimura disease? Most people may be hearing about it for the first time. According to statistics, only about 500 people worldwide have suffered from this disease so far! Kimura’s disease was first reported in 1937 by Kim Hsien-Tak in China, and was subsequently named after the Japanese scholar Kimura. It is a rare, etiologically unknown, long course; chronic benign, immunoinflammatory disease. The prevalent population is Oriental (China, Japan, Indonesia), occasionally seen in whites with a male to female ratio of about 6 to 10:1, and 12:1 has also been reported in the literature. The age of onset of the disease is reported to be 5 to 69 years in China and 10 to 76 years in foreign countries, with 20 to 40 years being the most common. Painless subcutaneous swelling and localized lymph node enlargement are the main manifestations; lymph node, soft tissue and salivary gland damage are predominant; head, neck and extremities are the most common sites. The disease should be differentiated from cervical lymph node tuberculosis, nasopharyngeal carcinoma, malignant lymphoma, eosinophilic granuloma and Kaposi’s sarcoma. The diagnosis requires histopathology, which mainly shows eosinophilic abscess formation and massive eosinophilic infiltration, and peripheral blood eosinophilia. The etiology and pathogenesis of the disease are unclear and may be related to immune dysfunction. Pathological studies have revealed mast cell hyperplasia and deposition of IgA, IgM and complement C3 around the hyperplastic small vessels, suggesting that the disease is an immune-mediated inflammatory reactive disease. It has been hypothesized that the disease may be associated with certain viral infections in which toxins alter the immunomodulatory role of T lymphocytes or induce IgE-mediated type I metaplasia, leading to the release of lymphokines, resulting in characteristic lymph node changes and associated renal damage, and thus Th2 cell immune dysregulation may be its etiology. The disease has a slow onset and long course, with involvement of the soft tissues of the head and neck, parotid and submandibular glands and superficial lymph nodes of the head and neck being the most common. The most common clinical manifestations are multiple soft tissue masses, mainly painless masses, mostly without self-consciousness, often located in the maxillofacial region, with unclear borders, adhesions to the skin, poor mobility, and a diameter of 1 to 10 cm, with a soft rubber-like texture in the early stages, gradually becoming hard and tough. Lymph node enlargement is also common, mostly in the subchin, submandibular and cervical areas. 40% to 100% of cases have pruritus and hyperpigmentation, mostly in the skin of the lump. In some cases, the lesions invade only the lymph nodes without subcutaneous masses. As the disease progresses, some patients may have a combination of renal injury after several months, mainly manifesting as nephrotic syndrome, and membranous lesions are the most common, with 12-16% of cases having proteinuria. In the present case, the main manifestation was bilateral cervical lymph node enlargement at the common site, but bilateral upper eyelid swelling has not been reported. Laboratory tests for this disease are characterized by a marked increase in the proportion and count of eosinophils in the peripheral blood picture, with the proportion mostly ranging from 10% to 20%, up to 69%, and elevated serum IgE. Eosinophils are significantly elevated in the bone marrow image of bone marrow aspiration, mainly in the late juvenile and mature stages. Imaging examination is non-specific and not easily distinguished from malignant tumors, lymphomas and hemangiomas, but there is generally no bone destruction, unlike malignant tumors. Pathologically, the mass has no perithelium and no obvious boundary with the surrounding tissues. Microscopically, we can see massive capillary hyperplasia, swelling and obvious proliferation of vascular endothelial cells, resulting in wall thickening and even lumen obstruction. There was a large number of lymphocytes and eosinophils infiltrating the vascular endothelial proliferation area, and lymphoid follicles were formed, and eosinophils were densely packed to form limited “eosinophilic small abscess” foci. The lymphatic follicles in the affected lymph nodes are actively proliferating, the growth centers are enlarged, and eosinophils infiltrate the cortex, medulla, and subepithelium, and in severe cases the lymph node structure disappears. The disease is a benign lesion with a good prognosis, but is prone to recurrence. It is sensitive to radiotherapy and is the preferred treatment at home and abroad, with an efficiency of more than 90%. The total recommended dose in China is 26-30 Gy for 2-3 weeks, with conventional split dose, and the irradiation field includes the lesion and swollen area. In clinical practice, single local tumor is usually removed surgically first, because the tumor boundary is unclear, surgery is not easy to remove completely, and it is very easy to recur after resection, the recurrence rate can be as high as 40%, clinical experience has found that adding small dose radiotherapy after surgery or combined glucocorticoid therapy after surgery can significantly improve the cure rate. Oral prednisone 30-60 mg/d can make the mass shrink significantly or disappear, but it is easy to recur after stopping the drug and should not be used as the only treatment, and in this case, the patient recurred in the hormone reduction. In the case of renal damage, corticosteroids and immunosuppressants can be used, but relapse is also common after discontinuation. For patients with recurrence or ineffectiveness after surgery or drug treatment, radiation therapy is equally effective, so if there are no contraindications and conditions allow, radiation therapy should be preferred. Single mass can be considered surgical excision, postoperative supplemented by low-dose radiotherapy and or glucocorticoid therapy; and for multiple patients can be surgery combined with radiotherapy, take the combination of cutting large and small, first put and then cut treatment to reduce recurrence. The main treatment means are ① surgery: after excision, the recurrence rate can be as high as 40%, so it is advisable to perform frozen section examination to ensure adequate excision range and reduce recurrence; ② radiation therapy: the best treatment dose is 26-30Gy, 2-3 weeks, the conventional split dose. The radiation field includes the lesion and the swollen area, and it has been reported in the literature that recurrence is rare if the dose is ≥26 Gy; ③ Steroid hormone therapy: oral prednisone tablets at 15 mg/time, 3 times/d from the beginning of radiotherapy. Most people believe that the addition of low-dose radiotherapy after surgery or the combination of glucocorticoid therapy after surgery significantly improves the cure rate.