A 35-year-old female health care worker with IgG deficiency was urgently admitted to our department due to pericardial effusion, which was diagnosed during a follow-up visit in an outpatient clinic. The IgG deficiency was detected over 10 years ago and classified by a hematologist as mild. There was no known history of IgG replacement therapy or chronic or recurrent infections. Two months prior to admission, she had been urgently hospitalized in a cardio-thoracic center due to an episode of cardiac tamponade evacuated with a pericardiocentesis. She had been discharged after 5 days in good condition and remained asymptomatic until a week before admission to our hospital. The pericardial fluid had been sent to diagnostics, but the test results remained unknown. The patient presented fatigue, dyspnea, and heart failure symptoms (New York Heart Association (NYHA) class III). Physical examination revealed tachycardia (heart rate 120 bpm) and hypotension (90/60 mm Hg). The patient denied weight loss, cough, fever, or night chills. Laboratory tests showed anemia (hemoglobin 8.9 mg/dl), elevated C-reactive protein level (CRP 64 mg/dl), no leukocytosis, and elevated CA-125 level (169.3 U/ml, reference < 35 U/ml). In the ECG, sinus rhythm with tachycardia (120 bpm), PR depression in inferior leads (II, III, aVF), and negative T waves in precordial leads (V2-V6) were found. Transthoracic echocardiography (TTE) revealed preserved left ventricular ejection fraction (LVEF, > 60%), pericardial effusion (> 30 mm of fluid), and impaired right ventricular function (right atrium and ventricle were collapsing; Figures 1 A, B). A diagnosis of cardiac tamponade was made, and urgent pericardiocentesis was performed. Over 450 ml of bright yellow, cloudy fluid was evacuated (Figure 1 C). The patient's condition improved significantly. In the angio-CT, hepatomegaly, a tumor in the uterus (defined by the radiologist as a uterine fibroid), and bilateral pleural effusion were described. Rheumatic diseases and HIV infection were excluded. The pericardial fluid's microscopic test revealed Mycobacterium tuberculosis, whereas the pleural fluid's microscopic test for Mycobacterium tuberculosis was negative. Initial anti-tuberculosis treatment was administered, and the patient was transferred to the pulmonology ward for further treatment. The tuberculosis was treated with rifampicin (6 months), pyrazinamide (3 months), ethambutol (3 months), and prednisolone (30 mg daily for 8 weeks) due to pericarditis. Two months after the initiation of TBC treatment, she was urgently admitted to the hospital due to jaundice, which was caused by TBC therapy. The pyrazinamide and rifam