Intracranial cholesteatoma in the thalamus: Uncommon location and atypical imaging findings.

Intracranial cholesteatoma is an uncommon condition that can occur anywhere in the intracranial cavity, but its occurrence in the thalamus is exceedingly rare. We present a case of thalamic cholesteatoma with atypical imaging findings and review the previous literature to explore the pathophysiological basis of these findings. A 55-year-old male presented to the hospital with right upper limb weakness and right ear hearing loss for more than 2 years. Imaging studies of the brain were performed, revealing a mixed density mass in the left thalamic region with calcification at the margin. Magnetic resonance imaging revealed a mixed signal intensity on T1-weighted and T2-weighted images, diffusion limitation on diffusion-weighted images, and ring enhancement on enhanced T1-weighted images. The mass caused mild obstructive hydrocephalus due to compression of the 3 ventricles and midbrain aqueduct. Thalamic cholesteatoma is an uncommon and often misdiagnosed lesion due to its unusual location and imaging characteristics. The pathophysiological basis of the atypical imaging findings associated with intracranial cholesteatoma is not well understood but may be related to the keratinization of the cyst lining or the presence of cholesterol crystals. Thalamic cholesteatoma should be considered in the differential diagnosis of thalamic lesions, especially in cases with calcifications or cystic components. Further studies are needed to better understand the pathophysiology of intracranial cholesteatoma and its associated atypical imaging findings.