Neuroimaging insights into poor prognosis paraneoplastic encephalomyelitis: A case report on a challenging diagnosis revealed by MR imaging in a patient with Hodgkin's lymphoma

Paraneoplastic encephalomyelitis (PEM) is a rare complication associated with malignancies, often presenting before the cancer diagnosis. A 42-year-old male with a history of chronic smoking presented with acute urinary retention and neurological deficits, all evolving in a febrile context with general deterioration. Laboratory tests were conducted, followed by a cerebral MRI which revealed multiple T2 and FLAIR hyperintense lesions in the periventricular and periaqueductal regions, medial temporal lobes, and bilateral postero-medial thalamus. Enhanced CT scans of the chest and abdomen identified multiple cervical, axillary, and inguinal lymphadenopathies. Subsequently, an ultrasound-guided biopsy of a cervical node was performed. His condition deteriorated rapidly, requiring intubation and sedation. A subsequent MRI revealed worsening cerebral and spinal cord lesions with new contrast enhancement in the brainstem. The differential diagnosis included toxic/metabolic and paraneoplastic causes. Biopsy results confirmed Hodgkin's lymphoma, leading to a diagnosis of progressive paraneoplastic encephalomyelitis (PEM). Despite adequate treatment, the patient's condition worsened, leading to death from pneumonitis and metabolic complications. This case underscores the importance of considering PEM in patients with neurological deficits and malignancy, with MRI playing a crucial role in diagnosis. Early detection and treatment are essential to improving outcomes.