P13 A rare case of Sjögren syndrome in a White woman with Kikuchi–Fujimoto disease
Authors: Goyal Sheena , Elston Georgina , Chahan Brinder 
Published: June 2023

Abstract
A 36-year-old White woman was seen in May 2022 for a rash on her upper back, shoulders, cheeks, forehead and extensor surfaces of the upper limbs. It had developed following sun exposure on the beach despite regularly applying SPF50. Over time, the rash became sore but exhibited no signs of vesicles or oozing. Of note, the patient had been recently diagnosed with Kikuchi–Fujimoto disease (KFD) following a lymph node biopsy. She gave history of Raynaud phenomenon since childhood, and arthralgia primarily affecting the small joints of hands. She also experienced episodic dry eyes, dry mouth, peripheral oedema, dyspnoea, abdominal pain and constipation. For the previous month, she had felt fatigued with some undocumented weight loss. Clinical examination revealed an erythematous rash with discrete nonblanching macules and plaques of varying sizes, oval-to-circular in shape, on the involved areas. Lymph nodes were not palpable. Differential diagnosis included cutaneous lupus, other connective tissue disorders, and—less likely—polymorphic light eruption. Skin biopsy showed focal compact hyperkeratosis and parakeratosis with focal subtle spongiosis, intraepidermal neutrophils and lymphocyte exocytosis, with the presence of perivascular and periappendageal chronic inflammation. There was mild basement membrane thickening with focal deposition of fibrinogen at the basement membrane zone on direct immunofluorescence. She was positive for anti-Ro antibodies, with a titre of 84 kU L−1 (normal &lt; 11 kU L−1). A diagnosis of Sjögren syndrome with KFD was made. The patient was advised on photoprotection with a high-potency topical steroid, and referred to rheumatology for review of her joint problems. After 4 weeks, the patient had only some improvement with topical therapy and was started on oral hydroxychloroquine. At the 12-week follow-up, there was significant improvement. Her skin was clear, with improvement in joint pain and fatigue. KFD, also known as necrotizing lymphadenitis, is a benign and self-limited disorder, characterized by regional cervical lymphadenopathy with tenderness, usually accompanied with mild fever and night sweats. Rarely, the skin and joints are involved. There is an established association between KFD and connective tissue disorders, especially Sjögren syndrome (Gates GA, Li Y, Magyar C, Sarantopoulos GP. Kikuchi–Fujimoto disease with unusual cutaneous findings. Am J Dermatopathol 2021; 43:e213–17). This is more prevalent among Asians and rarely reported in White people (Perry AM, Choi SM. Kikuchi-Fujimoto disease: a review. Arch Pathol Lab Med 2018; 142:1341–6), where it may cause diagnostic difficulties. This case highlights the importance of lateral thinking while formulating a differential diagnosis, despite the time pressures of a busy clinic. Although the reported prevalence of KFD among White people has been negligible (Perry et al.), it should not be dismissed solely based on a patient’s ethnicity. Timely and adequate management of rare conditions can reduce patient morbidity and improve their quality of life.