An indeterminate QuantiFERON TB-2G response for miliary tuberculosis, due to severe pancytopenia

We report the case of a 56-year-old man with miliary tuberculosis whose response to the QuantiFERON (QFT) TB-2G (Cellestis; South Melbourne, Australia) test was indeterminate due to pancytopenia (lymphocytopenia). The patient had severe lymphocytopenia due to either the miliary tuberculosis or immunosuppressive treatment with a corticosteroid; for the 2 years before admission, he had received corticosteroid treatment for Behçet's disease. The lymphocytopenia was also a complication of multiple organ failure and disseminated intravascular coagulation. A chest radiograph and computed tomography (CT) scan revealed a miliary shadow. After intubation performed because of acute respiratory failure, Mycobacterium tuberculosis was cultured from bronchoalveolar lavage fluid. We made a clinical diagnosis of miliary tuberculosis because M. tuberculosis was demonstrated in both lung and bone marrow specimens. However, immunologically, the tuberculin skin test was negative and the QFT-TB 2G test response was indeterminate, based on the CDC guideline. Although the QFT-TB 2G test has been used recently as a supportive method for the diagnosis of active tuberculosis, care must be taken in judging the condition of a patient with lymphocytopenia caused by severe underlying disease or immunosuppressive treatment. This patient was treated with antituberculous drugs 3 days after admission, but he died of multiple organ failure 6 days after admission.