Phagocytic syndrome is not a separate disease entity and the diagnosis requires at least 5 of the following 8 items: 1. fever that lasts >7 d with a temperature >38.5°C; 2. splenomegaly (≥3 cm at the subcostal margin); 3. hematocrit reduction (at least two or more lines of reduction in peripheral blood): hemoglobin <90 g/L, platelets <100 × 109/L, neutrophils <1.0 × 109 /L and not due to reduced bone marrow hematopoiesis; 4. hypertriglyceridemia (≥3.0 mmol/L) and/or hypofibrinogenemia (≤1.5 g/L); 5. phagocytosis found in bone marrow, spleen or lymph nodes; 6. reduced or absent NK cell activity; 7. ferritin ≥500ug/L; 8. significantly elevated soluble IL-2 receptor (sCD25) levels. The patient in this case met the diagnostic criteria. Phagocytic syndrome is mostly secondary to infection, trauma, and neoplasm, except for rare familial cases. Among neoplastic diseases, lymphoma secondary to phagocytic syndrome is the most common. Lymphoma is a malignant tumor of the lymphopoietic system, which can be divided into many different subtypes according to the pathological type of the tumor. In recent years, the incidence of lymphoma in China is on the rise. Many patients with lymphoma have fever as the first or even the only clinical manifestation and lack other diagnostic symptoms and signs, which makes the diagnosis difficult. For example, the present case of nasal NK/T-cell lymphoma belongs to non-Hodgkin's lymphoma, which is relatively rare and lacks specificity in early clinical symptoms. Therefore, patients with unexplained fever or manifestations consistent with phagocytic syndrome should be highly alert to the possibility of lymphoma. In addition to the improvement of relevant laboratory tests, a comprehensive and careful physical examination and detailed medical history inquiry are important. The patient had been seen in several hospitals and departments, but no attention was paid to the patient's medical history, and the physical examination was also inadequate. After being transferred to our department, Director Hao Hongling organized the whole department to conduct a meticulous physical examination of the patient and discovered the abnormal nasal manifestations that were easily ignored.