When rare becomes real: diagnostic challenges and use of a multidisciplinary team-based decision in primary pulmonary synovial sarcoma.

Primary pulmonary synovial sarcoma (PPSS) is a rare and aggressive malignancy accounting for 0.5% of lung cancers, with a 5-year survival rate of only 30%-50%. Diagnosis is challenging as it has no specific clinical or radiological features that distinguish it from other lung malignancies.We report a man in his 20s who presented with a 6-week history of cough and haemoptysis. Initial chest CT revealed a 2.2 cm endobronchial lesion in the left mainstem bronchus. Bronchoscopy confirmed the obstructing mass but initial biopsy was non-diagnostic. Positron emission tomography-CT scan demonstrated rapid tumour enlargement to 8.2 cm without evidence of distant hypermetabolic activity. CT-guided biopsy revealed spindle cell neoplasm, and immunohistochemistry along with SS18 fluorescence-in-situ-hybridisation confirmed a low-grade PPSS following a multidisciplinary team evaluation. Despite neoadjuvant chemotherapy, the tumour progressed; hence, he underwent sleeve pneumonectomy. This case highlights the importance of early referral to specialised lung centres and multidisciplinary care to enable timely diagnosis and improve outcomes in patients with rare pulmonary malignancies.