Kikuchi-Fujimoto's Disease or Histiocytic Necrotizing Lymphadenitis Following mRNA COVID-19 Vaccination: A Rare Case.

Kikuchi-Fujimoto disease (KFD), also known as necrotizing histiocytic lymphadenopathy, is a rare and benign lymph node disorder that mainly occurs in young women. It is clinically characterized by fever with tender and painful cervical lymphadenopathy mostly; however, all areas of lymph nodes can be involved. This disorder is often mistaken for malignant lymphoma or infection. The precise pathophysiology of KFD remains unknown, but it is theorized that it may be post-viral or associated with an autoimmune disease. The diagnosis is based on the histological analysis of the excised involved lymph node. The treatment is mainly supportive with favorable outcomes within a few weeks or months. In this case, we present a 24-year-old woman without a past medical history, who consulted for painful bilateral cervical lymphadenopathy associated with fever that has been evolving for one month following the coronavirus disease 2019 (COVID-19) vaccination. The initial diagnostic workup was performed and the diagnosis of KFD was confirmed based on the histopathological findings of the excised lymphadenopathy. Therapeutic management was based on oral corticosteroid treatment with clinical and radiological improvement after a few days without recurrence during follow-up. This article aims to report a rare case of KFD in a patient after receiving the messenger ribonucleic acid (mRNA)-based COVID-19 vaccine. Therefore, this case highlights the possible association between COVID-19 vaccination and KFD and this should be considered in the differential diagnosis.