An Incidental Discovery of Dandy-Walker Malformation on MRI in a 76-Year-Old Male Patient: A Case Report.

Dandy-Walker malformation is the most prevalent posterior fossa anomaly. Dandy-Walker variant, or Dandy-Walker complex, are terms devised to contrast those conditions that do not meet the standard of Dandy-Walker malformation. Dandy-Walker malformation is usually a congenital diagnosis. Our case calls attention to an extraordinary presentation of Dandy-Walker malformation in adulthood. A 76-year-old male patient initially presented to the Emergency Department at Dow University Hospital at Ojha Campus on the grounds of suspicion of a respiratory infection. COVID-19 was suspected; however, polymerase chain reaction (PCR) testing yielded a negative result. The patient later developed an erythematous and swollen left arm, which pointed towards a diagnosis of cellulitis, and the patient was managed accordingly. After being moved to the General Medicine Ward, our team noted that the patient was bed-bound and conducted a neurological exam, in which he presented with incoordination, less brisk and pendular deep tendon reflexes, and hypotonia in lower limbs, all suggestive of cerebellar involvement. The patient was also lethargic and was in a state of confusion, suggesting an altered mental status. Subsequent labs were completed, and bacterial pneumonia was confirmed on pleural fluid analysis. A CT scan of the head and an MRI scan of the brain were also ordered to investigate the reason for neurological involvement. The imaging displayed hallmarks signifying Dandy-Walker malformation, such as enlargement of the fourth ventricle, hypoplastic vermis, and posterior fossa anomalies.