Endocrine Abstracts

Introduction: Kikuchi-Fujimoto disease (KFD) is a benign self-limiting disease presenting with fever and lymphadenitis and mostly affecting adults younger than 40 years of age and of Asian descent. Its aetiology and pathogenesis are unknown though KFD often occurs in patients with concomitant autoimmune illness such as autoimmune thyroiditis or lupus erythematosus (SLE). We report a case of a patient with KFD and fluctuating thyroid function and thyroid autoantibody levels.

Case Report: A 35-year-old female patient presented with 4 months history of flu-like symptoms with fever, myalgia and persistent right axillary lymphadenopathy. She had past medical history of Graves’ disease diagnosed at the age of 15 when she presented with clinical and biochemical thyrotoxicosis (no treatment was given at that time). Eight years later she became hypothyroid with positive anti- TPO Ab and levothyroxine was commenced at 75 mg. However, after 6 years, her TFTs showed hyperthyroid picture despite gradually reducing and then withdrawing levothyroxine (TSH <0.01 mU/l, Free T4 13.3 pmol/l and Free T3 2.6 pmol/l, TSH receptor antibody (TRAb) <0.9 U/l, Anti-TPO Ab 615 U/ml). At the time of presentation with lymphadenopathy, she was found to have slightly raised anti-dsDNA levels (51.6 IU/ml) with negative ANA, ENA, negative Crithidia dsDNA and normal ESR (20 mm/hr), TFTs 2 months before were normal. Subsequent biopsy of right axillary lymph node showed necrotizing lymphadenitis with low ki67 score. SLE and other connective tissue disorders were excluded and diagnosis of Kikuchi-Fujimoto lymphadenitis was made. Following her confirmed diagnosis of KFD, she again developed fluctuating thyroid function tests and symptoms, which were alternating between mild hypothyroidism and hyperthyroidism. Her TRAb and anti-TPO at the time were 35.6 U/l and 615 U/ml respectively. Medical treatment was not recommenced as her symptoms were mild clinically and TFTs were not significantly deranged. KFD resolved spontaneously after 3 months and there has been no recurrence since. Her TFTs and antibodies continue to fluctuate (TSH 2.43 mU/l with normal Free T4 and Free T3, thyroid stimulating immunoglobulins 0.8 IU/l and anti-TPO Ab 626 U/ml) which raises the suspicion for presence of blocking and stimulating autoantibodies.

Conclusion: KFD is a rare usually self-limiting disease with unknown aetiology; SLE and autoimmune thyroid dysfunction, especially Hashimoto’s thyroiditis is often described in relation to it. Therefore, close follow up of these patients is required. The patient we report developed unusual for KFD significant fluctuations in her auto-antibodies status which are ongoing.