A case of pulmonary tuberculosis with false negative QuantiFERON TB-2G Test.

A 57-year-old man was admitted to our hospital with a high fever and productive cough. He had a previous history of total gastrectomy and splenectomy at the age of 45 years due to gastric cancer. He also showed severe macrocytic anemia with low vitamin B12, and an infiltrative shadow was found in the right lung on an X-ray. Sputum examination on admission revealed no significant pathogenic bacteria, and an acid-fast stain and a M. tuberculosis PCR test were negative. QuantiFERON TB-2G Test (QFT) was negative on admission. Because pneumococcal antigen in the urine was positive, we initially diagnosed pneumococcal pneumonia and treatment with antibiotics was started. However, symptoms were not resolved with several antibiotics, finally, a thoracoscopic lung biopsy under general anesthesia was performed for a definitive diagnosis. The biopsy showed epithelioid cell granuloma in the alveolar spaces, and the 8 weeks culture of sputum taken on admission revealed M. tuberculosis. Finally, a pulmonary tuberculosis was diagnosed and treatment with four drugs of HERZ was begun. We have encountered a case of pulmonary tuberculosis combined with a lobar pneumococcal pneumonia, and negative for QFT. In general, splenectomy is known as a risk factor of pneumococcal infection. And vitamin B12 deficiency due to gastrectomy is one of the risk factors for cellular immunity impairment and was possibly to the false negative QFT and development of TB.

[A case of radiation-related pneumonia and bilateral tension pneumothorax after extended thymectomy and adjuvant radiation for thymoma with myasthenia gravis].

A 62-year-old man was admitted to our hospital with a 2-month history of progressive cough and dyspnea. He had undergone thymectomy for thymoma with myasthenia gravis. Adjuvant radiation of 50 Gy had been performed until 6 months before the symptoms developed. Chest computed tomography showed infiltrative findings even outside the irradiated area. We diagnosed radiation-related pneumonia, and 30 mg per day prednisolone was initiated. On the final day, he developed bilateral tension pneumothorax. After chest tube drainage, the right S5 bulla was resected with video-assisted thoracoscopic surgery (VATS). The right pneumothorax caused the bilateral tension pneumothorax, because the right and left thoracic cavity communicated in the anterior mediastinum after thymectomy. We should be aware of the risk of bilateral tension pneumothorax following radiation-related pneumonia after extended thymectomy and adjuvant radiation in patients with myasthenia gravis.