A80-3-23 Pulmonary Sarcomatoid Carcinoma Masquerading as Tuberculosis: Two Cases in a TB-Endemic Region

Pulmonary Sarcomatoid Carcinoma(PSC) is a rare and highly aggressive subtype of non-small cell lung carcinoma (NSCLC), accounting for only 0.1-0.4% of lung cancers. Its diagnosis is often challenging due to its histologic heterogeneity, extensive necrosis, and radiologic similarity to chronic infections such as pulmonary tuberculosis(PTB). In TB-endemic areas, this overlap may result in diagnostic anchoring, leading to delays in cancer detection and treatment initiation. This report presents two cases of PSC initially treated as infectious disease, underscoring the diagnostic pitfalls and therapeutic implications of this rare entity. Case 1: A 56-year-old male, 120-pack-year smoker, presented with five months of productive cough and hemoptysis. Chest CT revealed a left upper-lobe mass suspicious for malignancy versus PTB. Despite first-line antituberculosis therapy, symptoms persisted and MTB PCR yielded rifampicin-indeterminate results. Two bronchoscopies showed chronic inflammation with necrotic debris but were inconclusive for malignancy. PET-CT demonstrated intense hypermetabolism (SUV 17.2). Due to high surgical risk, only a VATS-guided biopsy was performed, followed by endobronchial tumor debulking, which confirmed PSC. The patient received pembrolizumab every 21 days with weekly paclitaxel. Subsequent imaging demonstrated significant reduction of the suprahilar mass. Case 2: A 61-year-old female, 26-pack-year smoker, previously treated for PTB, presented with persistent productive cough and generalized weakness. CT scan showed a thick-walled cavitary lesion in the right upper lobe measuring 6.9 × 6.9 × 6.5cm, unresponsive to antibiotics. Bronchoscopy demonstrated extrinsic compression of the right upper lobe bronchus. CT-guided drainage yielded negative cultures for bacterial, TB, and fungal pathogens. She underwent VATS converted to mini-thoracotomy with right upper-lobe bilobectomy, confirming PSC on histopathology. The patient initiated paclitaxel-carboplatin-pembrolizumab but succumbed to massive hemoptysis after the first cycle. PSC commonly arises in the upper lobes and frequently exhibits cavitation or necrosis, often mimicking PTB. Small biopsies may fail to capture the sarcomatoid component, necessitating large surgical specimens for definitive diagnosis. In TB-endemic settings, radiologic overlap and confirmed MTB infection may mask underlying malignancy. PSC demonstrates poor response to conventional chemotherapy but exhibits high PD-L1 expression, supporting the role of immunochemotherapy. Early recognition and aggressive tissue sampling are crucial to improve outcomes. These cases highlight the importance of maintaining a high index of suspicion for malignancy in smokers with persistent or atypical pulmonary lesions, even in the presence of microbiologically confirmed TB. Timely tissue diagnosis through surgical or advanced bronchoscopic techniques is vital to enable early immunochemotherapy and potentially alter the dismal prognosis of PSC. This abstract is funded by: None