Kikuchi-Fujimoto disease and primary Sjögren's syndrome coexisting: A case-based literature review.

Kikuchi-Fujimoto Disease (KFD), also known as Kikuchi histiocytic necrotising lymphadenitis, is an extremely rare and benign condition that mostly affects young women. It is characterised by lymph node involvement with a predilection for the cervical region, commonly presenting with tender lymphadenopathy and a low-grade fever. The diagnosis requires excisional lymph node biopsy with immunohistochemical analysis. KFD is mostly self-limiting within a few weeks to months, with only some patients requiring symptomatic relief with non-steroidal anti-inflammatory drugs or corticosteroids, and a minority developing recurrent episodes of the disease. Importantly, it has been reported in association with systemic lupus erythematosus and, to a lesser extent, other immune-mediated inflammatory rheumatic diseases, such as Sjögren's syndrome, whose clinical presentation itself may include lymphadenopathy. In this paper, we present an unusual case of a woman with primary Sjögren syndrome (pSS) and a past medical history relevant for lymphoma, sarcoidosis, and thymoma, who later developed KFD, a particularly challenging diagnosis in this setting. We then performed a literature review of the association between KFD and pSS, gathering a total of 13 patients, and focusing epidemiological, clinical, and laboratory data.