Kikuchi-Fujimoto Disease: A Case of SARS-CoV-2 Infection Triggering the Rare Disease.

Kikuchi-Fujimoto disease (KFD), or histiocytic necrotizing lymphadenitis, is a rare, benign, and self-limited disease caused by subacute necrotizing regional lymphadenopathy. The etiology is unknown, although virus and autoimmune mechanisms have been proposed. Patients develop enlarged lymph nodes, fever, and, less frequently, extranodal signs. No specific laboratory test contributes to the diagnosis, and lymph node biopsy is the gold standard to define the diagnosis. The treatment is generally with supportive therapy and usually is spontaneously resolved within six months.  In this article, the authors present the case of a 41-year-old female with mild SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection 10 weeks before she was admitted to the emergency department (ED) due to cervical lymphadenopathies and fever lasting over three weeks. Physical examination revealed multiple lymphadenopathies on the submandibular and jugular regions, cutaneous rash, and hepatosplenomegaly. Blood tests showed elevated acute phase proteins, thrombocytopenia, and increased transaminases and lactate dehydrogenase (LDH). Computed tomography (CT) of the neck showed multiple adenopathies at levels I, II, III, and IV according to the Classification for Lymph Nodes from the American Head and Neck Society and American Academy of Otolaryngology on the right side. Excision biopsy was performed and histopathological examination confirmed KFD. A comprehensive analysis performed was unrevealing of an infectious or autoimmune cause and was assumed to be most likely triggered by SARS-CoV-2 infection given the timeframe correlation. KFD diagnosis is challenging and there are few reported cases of association with SARS-CoV-2 in the literature. Although further investigation is still needed to better understand the relation between them, it is important that physicians take SARS-CoV-2 infection and vaccination into consideration in KFD's differential diagnosis.