Severe destructive nasopharyngeal granulomatosis with polyangiitis with superimposed skull base Pseudomonas aeruginosa osteomyelitis

Abstract

Skull base osteomyelitis in the setting of granulomatosis with polyangiitis (GPA) is rare and entails significant diagnostic challenges. We present a case of a 65-year-old Caucasian man with a history of rheumatoid arthritis, off immunosuppression for 18 months, who presented with 2 years of chronic headaches, severe fatigue, saddle nose deformity and 20-kilogram unintentional weight loss. Maxillofacial CT revealed an extensive destructive sinonasal and erosive skull base process. Laboratory evaluation showed equivocal elevation of antiproteinase 3 antibodies with negative antineutrophil cytoplasmic antibody panel. Biopsy of the skull base/clivus revealed necrotising granulomatous inflammation with focal vasculitis consistent with GPA, and multiple bone cultures were positive for Pseudomonas aeruginosa This patient was diagnosed concurrently with GPA and P. aeruginosa skull base osteomyelitis. He was started on a 6-week course of cefepime intravenously and oral prednisone, with the plan to initiate rituximab infusion 2 weeks after initiation of antibiotic therapy.

Keywords: bone and joint infections; vasculitis.

Figure 1

(A) Axial T1 weighted image (T1WI) demonstrates loss of normal marrow signal at the skull base on either side of the clivus. There are gas and debris in the soft tissues extending from the nasopharynx to the skull base indicating necrosis. Note the abnormal common cavity between the sinus and nasopharynx from the destructive process. (B) Axial T1WI demonstrating infiltrating abnormal signal obliterating the normal fat planes at the medial aspect of the masticator space, involving the soft tissues of the nasopharynx and loss of the normal marrow signal at the skull base, all compatible with infectious involvement. Destruction of the nasal septum and right maxillary sinus wall, as well as the ethmoid air cell septae, is also partially visualised on this image.

Figure 2

Microscopic examination of nasal cavity tissue shows a poorly formed granuloma with palisading histiocytes (arrowhead).

Figure 3

An area of leucocytic vasculitis shown by (A) H&E stain and (B) Verhoeff-Van Gieson (VVG) stain. Infiltration through the vessel’s elastic lamella (arrowhead) is highlighted in the VVG stain.