Metastatic Adenocarcinoma of the Lung Mimicking Miliary Tuberculosis and Pott's Disease

Tuberculous spondylitis (Pott's disease) is among the frequent extra-pulmonary presentations of tuberculosis (TB). The global incidence of lung adenocarcinoma is on the rise, and it is a rare differential diagnosis of miliary shadows on chest imaging. It has a predilection to metastasize to ribs and spine in particular. There is a very close clinical and radiological resemblance in the presentation of spinal metastasis of lung cancer and Potts's disease. It poses a diagnostic challenge to clinicians particularly in TB endemic areas to arrive at an accurate diagnosis, leading to disease progression and poor outcome. We report a 54-year-old female patient presented with constitutional symptoms of on and off fever and back pain. Her chest X-ray revealed miliary shadows, and acid-fast bacilli (AFB) sputum smear and TB polymerase chain reaction (PCR) test came negative; radiological diagnosis of tuberculous spondylitis was done on computerized tomography (CT) chest and magnetic resonance imaging (MRI) spine. Subsequent bronchoscopy and bronchoalveolar lavage (BAL) cytology showed malignant cells and CT-guided lung biopsy confirmed lung adenocarcinoma with spinal and brain metastasis. Despite being started on chemo-immunotherapy and radiotherapy her outcome was poor due to advanced metastatic disease. This case highlights the significance of considering metastatic adenocarcinoma of the lung a rare but ominous possibility in the differential diagnosis of miliary shadows on chest imaging. Early bronchoscopy and biopsy must be considered in all patients presenting with miliary pulmonary lesions and spinal lesions to make a correct diagnosis, preventing an unnecessary delay in starting proper treatment and poor outcome. It also emphasizes the importance of better understanding the different radiographic features of the two common mimics, spinal tuberculosis, and metastatic spinal tumors.