Abstract
Hypertrophic pachymeningitis is a rare inflammatory condition that leads to the thickening of the dura mater, either due to unknown or identifiable secondary causes. Granulomatosis with polyangiitis is a notable causative agent, and hypertrophic pachymeningitis is the initial presentation in certain cases. The diagnosis of hypertrophic pachymeningitis is aided by contrast-enhanced MRI, although distinguishing between normal and abnormal dural enhancement can be challenging using contrast-enhanced T1WI. This study highlights the case of an 80-year-old woman diagnosed with hypertrophic pachymeningitis secondary to antineutrophil cytoplasmic antibody-associated granulomatosis with polyangiitis, where contrast-enhanced FLAIR played a crucial role in distinctly identifying abnormal dural enhancement and differentiating it from normal dura. In conclusion, although contrast-enhanced T1WI remains indispensable, contrast-enhanced FLAIR can serve as a valuable complementary tool in MRI study sequences for the diagnosis of hypertrophic pachymeningitis.