Pulmonary tuberculosis mimicking radiation pneumonitis in a patient with neck malignancy: A case report

RATIONALE: Primary or reactivation pulmonary tuberculosis (TB) is frequent in immunocompromised patients such as those with human immunodeficiency virus (HIV) infection, chronic renal failure, poorly controlled diabetes, and hematologic malignancy. Immune system of patients with solid-organ cancer can be also altered by malignancy itself or chemotherapy. However, information on the effect of radiation on patient's immunity is scarce. Herein, we present a case of pulmonary TB occurring in a radiation field that mimics focal radiation pneumonitis in a patient who has received curative chemoradiation therapy for neck malignancy. We also performed literature review to understand the impact of radiation therapy on patients’ immunity. PATIENT CONCERN: A 56-year-old male patient visited our hospital with a palpable mass in the right supraclavicular fossa which was later confirmed as metastatic squamous cell carcinoma. After completion of concurrent chemoradiation therapy, a focal consolidation was developed in the right upper lobe apex where radiation was applied. The patient did not have any symptoms or signs of infectious disease. DIAGNOSIS: Pulmonary TB was diagnosed through polymerase chain reaction (PCR) test and culture of sputum. INTERVENTION: Anti-TB medication was started. OUTCOME: The patient was tolerable to anti-TB medication and the size of TB lesion gradually decreased. LESSON: A suspicion of pulmonary TB should be given to patients with new infiltrates in radiation port due to impact of radiation therapy on local infection barriers and patients’ immune system.