Ovoid nodule of T2 hypointensity and T1 isointensity in the anterior hemispheric fissure with peripheral enhancement, adjacent dural/leptomeningeal enhancement and adjacent parasagittal frontal lobe vasogenic edema. This finding corresponds with hyperdensity on a recent head CT. The findings are nonspecific and may represent intracranial involvement of patients recently diagnosed granulomatosis with polyangiitis (Wegener's granulomatosis) or CNS lymphoma. The MR imaging appearance is atypical for acute subdural hematoma.

The collection of findings: Cavitary lung lesion and sinusitis should raise concern for granulomatosis with polyangiitis. A brain biopsy was performed to further evaluate the extra-axial mass.

Pathology:

Brain, Biopsy: Designated falcine; left frontal craniotomy, biopsy under stealth guidance:

Necrotizing granulomata.

Lung biopsy: 

Compatible with ANCA positive vasculitis (Wegener's granulomatosis) with necrotizing granulomas.

Findings are compatible with CNS involvement by granulomatosis with polyangiitis.