DOI: https://doi.org/10.36347/sjmcr.2026.v14i05.090

Pages: 1239-1242

Paraneoplastic neurological syndromes are rare immune-mediated conditions that may exclusively reveal an otherwise asymptomatic malignancy, particularly small cell lung carcinoma. We report the case of a 64-year-old man with type 2 diabetes mellitus and a significant smoking history who presented with a two-week history of progressive diffuse paresthesias without motor deficit or systemic complaints, initially suggestive of diabetic neuropathy. Neurological examination revealed hyporeflexia without objective sensory loss. Laboratory investigations demonstrated an inflammatory syndrome with preserved glycemic control. Electrodiagnostic studies identified a pure sensory axonal polyneuropathy inconsistent with typical diabetic neuropathy. Given the rapid progression of symptoms and the patient’s smoking history, chest imaging was performed and revealed a large right hilar mass with mediastinal lymphadenopathy. Bronchoscopic biopsies confirmed small cell lung carcinoma with a high proliferative index. The patient experienced sudden clinical deterioration and died before initiation of oncologic treatment. This case highlights that paraneoplastic neurological syndromes may represent the sole manifestation of an otherwise clinically silent malignancy and should be considered in rapidly progressive or unexplained neurological presentations.