34 year-old  with dizzy spells and frequent headaches




 
CT axial bone windows


     
CT axial postcontrast soft tissue windows                                               
   
 
Axial noncontrast T1 and T2


 
Axial FLAIR and coronal T2 fat sat


Findings:

CT:  Lytic relatively well circumscribed lesion in the petro-clival junction region
MR:  High T2 and FLAIR and intermediate T1 signal intensity somewhat heterogeneous

DDX:

Chordoma, chondrosarcoma, metastasis, atypical cholesterol  granuloma



Diagnosis:

Cholesterol  granuloma

Discussion:

The well circumscribed border favors a benign lesion although this case is atypical on MR since these lesions usually show high T1 signal. The pathogenesis is usually related attributed to eustachian tube dysfunction, leading to mucosal edema and chronic hemorrhage. The encapsulated blood products undergo degeneration and provoke a chronic inflammatory response.



Submitted by John Rhee, MD, UW Neuroradiology Fellow

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