Kikuchi-Fujimoto disease is a rare benign disease which is associated with histiocytic necrotizing lymphadenitis. KFD is endemic in Asia, especially affects young women with only a few cases reported from Europe making its diagnosis very   difficult. KFD is usually characterized by symptoms of fever, night sweats and tender lymphadenopathy. The other less common presenting clinical manifestations include generalized lymphadenopathy, weight loss, enlargement of spleen, skin rash, joint pain, decrease in weight, nausea, vomiting and central nervous system involvement. The most commonly involved lymph nodes are cervical, followed by axillary and other lymph nodes. The affected lymph nodes have the characteristic of been solid, mobile, and painful but not been suppurative [6,8]. It is a self-limiting disease which resolves within several months and has a recurrence rate of 3-4% [10]. It commonly affects females under 30 years of age (mean age-29) [11]. We present a case of 7year old boy with a single cervical lymph node presenting with constitutional symptoms.

Two possible etiologies of KFD have been identified: viral and autoimmune. The first one is the viral etiology which consists of a hyper-immune response in genetically susceptible patients. The second one is the autoimmune etiology likely because of the relationship between KFD and autoimmune diseases with many reports referring KFD as an early stage of SLE [6]. In our study, both viral as well as autoimmune serology was unremarkable (ANA=negative). There also have been implication of Bacteria and parasites have in the pathogenesis of KFD with controversial results [12,13].

No specific laboratory tests or instrumental examination can suggest a diagnosis of KFD. The usual laboratory alteration in KFD includes leukopenia occasionally with atypical peripheral blood lymphocytes, anemia, or increased inflammatory markers [14,15]. Rise in LDH and transaminases may rarely be seen. In our patient, we had increase in inflammatory markers such as ESR and CRP along with increase in LDH while Liver enzymes were normal.

No imaging feature is diagnostic of KFD and it is sometimes difficult to distinguish KFD from lymphoma and other nodal diseases with necrosis. The finding of distinctive lymphadenopathy pattern consisting of many small clustered lymph nodes can be noted on ultrasounds, CT scan, and magnetic resonance with a carefully interpretation [9,16,17]. There is limited diagnostic accuracy when it comes to Fine-Needle Aspiration Cytology (FNAC) in diagnosing KFD which is approximately 56% [18-20]. Hence, lymph node biopsy is the only way to reach a correct diagnosis of KFD. In our case, we had painful and tender cervical lymphadenopathy, so we suspected glandular fever and other viral etiologies. Ultrasound showed matted lymph node so initially we suspected TB lymphadenitis as well as we live in TB endemic area. Workup for tuberculosis was negative in our case with unrevealing CT Chest, abdomen and pelvis. So, we decided to go for excisional cervical lymph node biopsy which revealed features of Kikuchi`s lymphadenitis that necrotizing tissue, composed of abundant karyorrhectic debris, fibrinoid necrosis of small arterioles and collection of large mononuclear cells.

Despite of advances in medical sciences, no definitive treatment for KFD has been discovered up to date. KFD is usually a self-limiting condition; however, milder disease can be controlled by NSAIDs and antipyretics. Reports also suggest that the use of corticosteroids in case of persistent or more severe symptoms, as in patients with extra nodular involvement, such as the Central Nervous System (CNS) and lungs. The symptomatic patients usually improve with short pulses of corticosteroids with hydroxychloroquine or IV corticosteroids reserved for unresponsive patients or patients with complicated diseases. The best treatment options include alternating high-dose corticosteroids and IV immunoglobulin .⁵ In our case, treatment with NSAIDs was commenced after the histological results were obtained because of persistence of fever, fatigue, and night sweats. At 2 months follow up, the patient demonstrated improvement in clinical and laboratory parameters while at six-month follow-up, the patient was asymptomatic.

So, we highlight here that KFD is a rare disease that sometimes proves to be a diagnostic dilemma. It should be kept in mind in the differential diagnosis of lymph node enlargement because it has an altogether different therapeutic approach as compared to other entities and misdiagnosis can lead to polypharmacy or unnecessary treatment [9,21]. Various differential diagnosis should be considered along with KFD which include infections, Granulomatous lymphadenitis, connective tissue diseases, and lymphoproliferative disorders [9,22].

This is the first case which has been reported from Pakistan, especially in a young boy which is against the odds as it is the disease which is more common in females and has autoimmune etiology