Pulmonary Sarcomatoid Carcinoma Initially Misdiagnosed as Aspergillosis: A Diagnostic Challenge

Pulmonary sarcomatoid carcinoma (PSC) is a rare and aggressive malignancy that often presents atypically, leading to incomplete diagnosis. We report a 55-year-old male with chronic obstructive pulmonary disease who presented with productive cough and haemoptysis. Initial bronchoscopy revealed fungal hyphae consistent with Aspergillus infection. The misleading clinical presentation led to an incomplete diagnosis. Subsequent lung biopsy and immunohistochemistry confirmed PSC harbouring an EGFR L858R mutation. Despite the presence of a targetable mutation, the patient showed a poor response to EGFR-targeted therapy. This case highlights the diagnostic challenges and therapeutic complexities when PSC coexists with an airway fungal infection.