Lurking beneath the Murky Waters: Tuberculosis Presenting as a Mass Lesion in the Lung

Sir, Tuberculosis and lung cancer share several clinical similarities, including a persistent cough, hemoptysis, weight loss, fatigue, and chest pain. Radiological imaging further complicates the diagnostic process, as both tuberculosis and lung cancer can manifest as infiltrates, nodules, or masses on chest radiography and computed tomography (CT) scans. The overlapping clinical and radiological presentation often leads physicians down a diagnostic path focused on malignancy, potentially overlooking the possibility of an underlying tuberculosis infection. We had a 42-year-old female patient who is a diagnosed case of bipolar disorder on psychotropic medication presenting to us with complaints of fever, weight loss (5-6 kg) and anorexia of 1-month duration. The fever was insidious in onset, low grade, and intermittent with no evening rise, chills, or rigors. She had received multiple courses of oral antibiotics before being reviewed at our center. On physical examination, she had a heart rate of 89/min, blood pressure of 110/68 mmHg, and respiratory rate of 23/min and was maintaining a saturation of 98% on room air. She had pallor, but there was no icterus, cyanosis, pedal edema, or peripheral lymphadenopathy. She was alert and oriented and had bronchial breath sounds in the left infraclavicular and axillary regions. On evaluation, she had a hemoglobin of 8.3 g/dl, total leukocyte count – 9200/cumm (neutrophil – 91%, lymphocyte – 2%, eosinophil – 6%, and monocyte – 1%), platelets – 2,54,000/cumm, urea – 28 mg/dl, creatinine – 1.4 mg/dl, alanine transaminase – 65 U/L, and aspartate transaminase – 73 U/L. She tested negative for human immunodeficiency virus and hepatitis B and C virus. The erythrocyte sedimentation rate was elevated (39 mm/h), and her electrocardiogram recorded a normal sinus rhythm. Chest radiography revealed homogenous opacity in the left upper zone Figure 1. Sputum Gram stain, Ziehl–Neelsen stain, and MTB GeneXpert were negative. She was initially diagnosed as a case of community-acquired pneumonia and was started on empirical antibiotics and supportive therapy. The patient continued to have spikes of fever despite 4 days of antibiotics. A noncontrast CT scan (NCCT scan) of the chest taken for further evaluation demonstrated a large dense mass lesion in the left upper lobe with small nodular calcification focus and cutoff of the left upper lobe bronchus. The mass measured 31.4 mm × 35.3 mm × 2.75 mm with anterior pleural attachment with mediastinal involvement and satellite nodular opacification around it suggesting a bronchogenic carcinoma. There was associated mediastinal lymphadenopathy. Positron emission tomography (PET) revealed an avid lesion (SUVmax: 18.36) in the left upper lobe of the lung with multiple avid cervical and mediastinal lymph nodes Figure 2. She was suspected to have lung cancer; as a part of the workup, video bronchoscopy was done which revealed a normal tracheobronchial tree. Bronchoalveolar lavage (BAL) was taken from the left upper lobe, and NCCT-guided biopsy was taken from the lung lesion. Histopathological examination of the lung tissue was negative for malignant cells but showed diffuse chronic inflammatory changes with multiple small necrotizing granulomas and interstitial fibrosis Figure 3. BAL GeneXpert was positive for Mycobacterium tuberculosis with no rifampicin resistance. The patient was diagnosed as a case of pulmonary tuberculosis and was started on first-line antituberculosis therapy (ATT). She had symptom resolution within a week of starting ATT and chest radiography taken after 2 weeks showed significant symptom resolution Figure 4.Figure 1: Chest radiography taken on presentation revealing dense homogenous opacity in the left upper zoneFigure 2: Positron emission tomography–computed tomography of the patient revealing fluorodeoxyglucose-avid mass lesion in the left upper lobeFigure 3: Histopathological examination of the lung tissue showing diffuse chronic inflammatory changes with multiple small necrotizing granulomas and interstitial fibrosisFigure 4: Repeated chest radiography after 2 weeks of antituberculosis therapy showing resolution of left upper zone opacitiesMultiple case reports have highlighted the clinical difficulty which we faced in managing this patient.1-3 The difficulty arises due to overlapping clinical and radiological presentations. Both the disease processes can have similar avid lesions in PET with some researchers estimating an optimal SUVmax cutoff as 8.45 for discriminating between pulmonary tuberculosis and lung cancer.4 Molecular diagnostic techniques, such as nucleic acid amplification tests, and histopathological examination can aid in the early identification of tuberculosis. Due to these reasons, health-care professionals must maintain a high index of suspicion for tuberculosis, particularly in regions with a high prevalence of the disease. Utilizing a combination of molecular diagnostic tests and invasive procedures when necessary can help establish an accurate diagnosis and initiate timely and appropriate treatment. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.