A Case of Appendicitis Due to Burkitt Lymphoma Masking the Systemic Symptoms of Rapidly Progressing Burkitt Lymphoma.

Introduction: Primary malignant lymphoma of the appendix is a rare disease, and primary Burkitt lymphoma of the appendix has been reported very rarely in Japan. Burkitt lymphoma is an aggressive lymphoma that progresses more rapidly than other malignant lymphomas, making it sometimes difficult to distinguish between systemic symptoms, such as fever associated with lymphoma progression and fever caused by appendicitis.

Case Presentation: A 21-year-old man underwent open appendectomy after antibiotic treatment for acute appendicitis proved ineffective. Postoperative pathological findings confirmed acute appendicitis. Antibiotics were continued after surgery, and the patient's fever and abdominal symptoms gradually improved. However, abdominal distension recurred on the 18th day of hospitalization. Blood tests showed a re-elevation of the white blood cell count, suggesting a postoperative intraperitoneal abscess. Despite further antibiotic treatment, fever and leukocytosis persisted. On the 28th day of hospitalization, abnormal lymphocytes were detected in the peripheral blood, and we realized that the persistent fever was due to systemic symptoms of malignant lymphoma rather than a complication of appendicitis. On the 30th day, the patient was referred to the hematology department and subsequently diagnosed with Burkitt lymphoma. Chemotherapy was initiated on the 40th day of hospitalization. At the time of this writing, the patient had remained alive without recurrence for 4 years 3 months postoperatively.

Conclusion: In this case, symptoms of acute appendicitis and systemic symptoms of malignant lymphoma appeared simultaneously. As a result, the systemic symptoms of malignant lymphoma were misdiagnosed as postoperative complications, leading to a delay in diagnosis. Primary appendiceal Burkitt lymphoma is extremely rare, and its clinical features remain unknown. It is important to recognize that primary appendiceal Burkitt lymphoma can present with systemic symptoms concurrently with appendicitis. Surgeons should be aware of the clinical features of appendicitis caused by Burkitt lymphoma, which differ from those caused by other appendiceal tumors or malignant lymphoma.