Occam's Razor or Gamma Knife?

The patient was lost to follow-up for six months. She then presented again with pain and visual loss in the right eye. Visual acuity had decreased to 20/400 OD. Repeat MRI showed increased size of the mass and new involvement of the right pre-chiasmal optic nerve. A fronto-orbital craniotomy and decompression of the mass was performed. Pathology revealed fibrous tissue with an extensive inflammatory infiltrate, including granulomas, histiocytes, and scattered giant cells, along with perivascular inflammation and necrosis. The results were consistent with a diagnosis of Wegener's granulomatosis (WG). Upon further questioning, the patient revealed a history of a kidney biopsy showing WG over 12 years prior as the cause for her end-stage renal disease. She was placed on oral prednisone due to an adverse reaction to rituximab. Compliance and follow-up remain poor. Visual acuity at the last follow-up was 20/50 OD with an unchanged motility exam. WG is a systemic, necrotizing, granulomatous vasculitis of unknown etiology, first described in 1939 [1]. Diffuse small and medium size vessel involvement in WG classically leads to upper and lower respiratory tract, and kidney involvement. Central nervous system involvement has been reported in approximately 22-54% of cases of WG [2]. Most commonly this involves peripheral neuropathy resulting from vasculitis affecting the small vessels. Pituitary involvement is extremely rare, and the exact mechanism is unknown. When it does occur, it usually leads to central diabetes insipidus with loss of the normal hyperintense signal in the posterior pituitary. However, we are not aware of any similar reports of WG mimicking a pituitary prolactinoma [2,3].