Report of a rare case of histiocytic necrotizing lymphadenitis with bilateral pleural effusion diagnosed via cervical lymph node biopsy.

CONTEXT: Histiocytic necrotizing lymphadenitis (HNL) is a rare disorder that is often benign and self-limiting. There have been reports of co-occurrence of HNL with other diseases, including systemic lupus erythematosus, hemophagocytic syndrome and antiphospholipid syndrome. CASE REPORT: Here, we report a case in which a patient experienced unexplained fever, swelling of the cervical lymph node and bilateral pleural effusion and was ultimately diagnosed with HNL based on results from a lymph node biopsy. After treatment with glucocorticoid, the patient regained normal body temperature, the swelling of the lymph nodes disappeared and the pleural effusion was reabsorbed. CONCLUSIONS: The pathogenesis of HNL remains unclear, and pleural effusion is rarely reported in HNL patients. We presented this case to improve diagnostic awareness of this condition among clinicians and help reduce the likelihood of misdiagnosis.