Posterior Cortical Atrophy Masked by a Pituitary Macroadenoma: Diagnostic Challenges in the Setting of Dual Visual Pathology.

Posterior cortical atrophy (PCA) is a rare neurodegenerative syndrome characterised by progressive visuospatial and visuoperceptual dysfunction. Diagnosis is frequently delayed, particularly when coexisting visual pathology provides an alternative explanation for symptoms. A man in his sixties with a known pituitary macroadenoma and right homonymous hemianopia presented with a four-year history of insidious visual and functional decline. Prior serial perimetric assessments demonstrated progressive, inconsistent field loss not explained by stable chiasmal compression. Neurological assessment revealed prominent posterior cortical deficits, including features of both Balint and Gerstmann syndromes. MRI demonstrated parietal-predominant cortical atrophy, and fluorodeoxyglucose-18 Positron Emission Tomography (18F-FDG-PET) confirmed marked parieto-occipital hypometabolism, establishing a diagnosis of PCA. This case illustrates how established anterior visual pathway disease can delay recognition of concurrent neurodegenerative pathology. For patients with known afferent visual impairment, clinical indicators to prompt consideration of a cortical pathology and a proposed structural assessment framework are discussed.