The Curious Case of Pyrexia of Unknown Origin

Pyrexia of unknown origin (PUO) is a diagnostic challenge for many clinicians. The causes of PUO are diverse. Infections and malignancies are the most common causes of PUO. There are many rare causes of PUO like aorto-arteritis, Stills disease, sarcoidosis, and temporal arteritis. However, extensive diagnostic tests are required for diagnosis in some cases. We had a 47-year-old lady who presented to us as a rare case of PUO. After extensive investigations she was diagnosed as a case of Idiopathic Hemophagocytic Lymphohistiocytosis (HLH). HLH is a rare disease with high mortality. Most frequently the diagnosis of HLH is missed.