Painless postauricular mass: An atypical presentation of Kikuchi-Fujimoto disease

Kikuchi-Fujimoto disease, also known as histiocytic necrotizing lymphadenitis, is a rare self-limiting condition primarily characterized by cervical lymphadenopathy and fever. This report presents the case of a Han Chinese woman in her early 40s who had no significant medical history and presented with a painless mass behind her ear. She denied systemic symptoms such as fever, night sweats, or weight loss. Physical examination revealed a non-tender, mobile mass in the postauricular region. Initial ultrasound suggested a small cystic structure, and the mass was subsequently excised. Initial pathology reported reactive lymphoid hyperplasia; however, due to atypical presentation, immunohistochemical staining was performed, which was positive for multiple markers consistent with Kikuchi-Fujimoto disease. The patient did not receive specific treatment and remained asymptomatic with no recurrence at 1-month follow-up. The patient lacked typical lymph node pain and fever. The absence of typical lymph node pain and fever in the patient in this case highlights the importance of considering Kikuchi-Fujimoto disease in the differential diagnosis of painless lymphadenopathy and underscores the significance of histopathological examination and immunohistochemical analysis in reaching a definitive diagnosis.