Kikuchi-Fujimoto Disease of Mesenteric Lymph Nodes Mimicking Acute Appendicitis
Executive Summary
Kikuchi-Fujimoto disease (KFD), also known as histiocytic necrotizing lymphadenitis, is a rare, benign, and self-limiting condition characterized by regional lymphadenopathy of unknown etiology. While it most frequently presents as cervical lymphadenopathy in young adults, involvement of the mesenteric lymph nodes is uncommon and poses a significant diagnostic challenge. Because its clinical presentation can mirror acute appendicitis—including right iliac fossa (RIF) pain, fever, and elevated inflammatory markers—patients often undergo unnecessary major surgical interventions, such as laparotomy or hemicolectomy.
Diagnosis is definitively established through histopathological examination, as clinical findings and imaging often overlap with more severe conditions like lymphoma or systemic lupus erythematous (SLE). Management is primarily supportive, with most cases resolving spontaneously within one to four months.
Clinical Overview of Kikuchi-Fujimoto Disease
KFD was independently described in 1972 by Kikuchi and Fujimoto. It is increasingly recognized globally as a critical differential diagnosis for lymphadenopathy.
Epidemiology and Etiology
Demographics: The average age of presentation is between 20 and 30 years. Recent data suggests no racial predilection and a 1:1 male-to-female ratio, contradicting earlier reports of a female and East-Asian predominance.
Aetiology: The exact cause remains unknown, though KFD is often associated with various infectious, autoimmune, and neoplastic conditions.
Associated Pathogens:
Epstein-Barr Virus (EBV)
Human Herpes Viruses 6 and 8
Herpes Simplex Virus
Cytomegalovirus
Adenovirus, Parvovirus B19, Varicella Zoster, and Dengue Virus
Yersinia sp. and M. azulgia
Symptomatology
The "cardinal symptoms" of KFD occur in a subset of patients and include:
Common: Fever, myalgia, headaches, and sore throats.
Less Frequent: Abdominal pain, weight loss, nausea, vomiting, and night sweats.
Physical Signs: Rash, hepatosplenomegaly, and neurological signs (typically associated with extranodal disease).
Diagnostic Challenges and Differentials
KFD is frequently misdiagnosed due to its varied presentation and lack of characteristic laboratory or imaging features.
Differential Diagnoses
The clinical and laboratory findings of KFD overlap significantly with several serious conditions:
Malignancies: Hodgkin’s and non-Hodgkin’s lymphomas, nodal metastases from adenocarcinoma, and plasmacytoid T-cell leukaemia.
Autoimmune/Inflammatory: Systemic lupus erythematous (SLE), sarcoidosis, and Kawasaki disease.
Infections: Tuberculosis.
Diagnostic Limitations
Laboratory Tests: Blood tests are often non-specific. Findings may include slight thrombocytopenia, neutropenia with lymphocytosis, and elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP).
Imaging: CT and MR scans may show small clustered lymph nodes, but these are not definitive and can mimic lymphoma or tuberculosis.
Cytology: Fine needle aspiration cytology (FNAC) has a limited diagnostic accuracy of approximately 56.3%, often leading to misdiagnosis.
Mesenteric Lymphadenopathy and Surgical Mimicry
Involvement of the mesenteric lymph nodes is rare but clinically significant because it mimics acute appendicitis.
Case Study Synthesis: 26-Year-Old Male
A recent case highlights the risks of KFD-driven surgical intervention:
Presentation: A 26-year-old male presented with pyrexia (37.9°C) and umbilical pain that migrated to the right iliac fossa (RIF).
Laboratory Findings: White cell count (WCC) was 10.2 (near normal), but CRP was significantly elevated at 125 mg/L.
Surgical Findings: An emergency laparotomy revealed a normal appendix but a hard, irregular mass in the caecum that had perforated. Multiple enlarged lymph nodes were found in the mesentery extending to the superior mesenteric artery.
Procedure: A radical right hemicolectomy was performed.
Histopathological Findings
Definitive diagnosis requires an excision lymph node biopsy. Key microscopic features include:
Necrosis: Uneven paracortical areas of coagulative necrosis with karyorrhectic debris (nuclear fragments).
Cellular Composition: Large numbers of histiocytes and plasmacytoid cells at the margins of necrotic areas; predominance of T cells (CD8+ and CD4+).
Architecture: Distortion of normal nodal architecture; lymphoid follicles may be replaced by apoptotic debris in early necrosis.
Specific Exclusions: Absence of neutrophils and plasma cells is a common feature.
Management and Prognosis
KFD is generally a self-limiting condition with a favorable outlook.
Conclusion for Clinical Practice: A high index of suspicion for Kikuchi-Fujimoto disease is necessary when evaluating unusual presentations of mesenteric lymphadenopathy. Maintaining this suspicion can prevent major surgical procedures in cases where the condition would otherwise resolve with supportive care.
