不明熱為臨床診斷上常遇到的難題。本文描述一個困難診斷的不明熱個案，藉由討論不明熱的評估與診斷流程，並著重於血液與生化檢查方面。文中呈現一位64歲女性，以兩個月不明熱的臨床表現，最後診斷為骨髓中的惡性淋巴瘤。在不明熱的病人中，血紅素、血鐵質等指標，都可能暗示著血液疾病的診斷。至於發炎指標、潛伏結核菌的檢查結果，在不明熱的病患都需要小心判讀。

Workup of fever of unknown (FUO) is challenging due to non-specific clinical manifestations. We report the case of a patient who presented with FUO for two months. Further workup with laboratory test, image study and tissue sample confirmed the diagnosis of lymphoma. Our case illustrates the importance of careful interpretation of laboratory test during the workup of FUO. For example, abnormal ferritin and hemoglobin levels are associated with higher risk of hematology maligancy.