Paraneoplastic Cushing Syndrome Unmasking Small Cell Lung Cancer: A Rare Presentation.

We present a case of a middle-aged woman who presented with chest pain and shortness of breath. Laboratory tests revealed persistent hypokalaemia, hyperglycaemia, and metabolic alkalosis despite treatment. Imaging identified a mass near the right hilum suggestive of lung malignancy. Endocrine evaluation showed markedly elevated cortisol and adrenocorticotropic hormone levels, consistent with paraneoplastic Cushing syndrome caused by ectopic hormone production. The analysis of the lung biopsy obtained through bronchoscopy confirmed the diagnosis of small cell lung cancer (SCLC). The patient was treated with metyrapone and spironolactone to stabilise her metabolic abnormalities and was subsequently referred for chemotherapy following a multidisciplinary team review. This case highlights the importance of recognising paraneoplastic syndromes as atypical presentations of malignancy and emphasises the role of a coordinated, multidisciplinary approach in diagnosis and management.