Fluorine-18-fluorodeoxyglucose PET/CT rare finding of a unique multiorgan involvement of Wegener's granulomatosis.

Wegener's granulomatosis (WG) is an uncommon autoimmune disorder, which mainly involves the blood vessels, kidneys and respiratory tract. We report an interesting case of WG with unusual multiorgan involvement in a young male who presented with a short history of right-sided otalgia, nasal obstruction and a right parotid mass. His initial CT and MRI scans showed a large parotid mass with features suggestive of malignancy with bilateral cavitating pulmonary nodules suggesting metastatic disease. The imaging-based differential diagnosis was squamous cell carcinoma or adenoid cystic carcinoma. The microscopic findings on ultrasound-guided biopsy of the parotid mass were, surprisingly, those of acute necrotising granulomatous inflammation with some features suggestive of a vasculitic process. A multidisciplinary team discussion and further investigation resulted in the additional findings of haematuria, raised erythrocyte sedimentation rate and positive serum cytoplasmic anti-neutrophil cytoplasmic antibody test, which led to the diagnosis of WG. Subsequently, the patient developed acute urinary retention owing to gross prostatic enlargement related to further disease involvement, which was confirmed with a positive biopsy. Fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/CT scan showed disease distribution at the right maxillary sinus/nasal cavity, right parotid, mediastinum, lungs and prostate. To our knowledge, this is the first reported 18F-FDG PET/CT case with multiorgan involvement in a single WG patient. The patient has improved both clinically and on imaging after appropriate treatment with immunosuppressive therapy and steroids. Although 18F-FDG PET/CT imaging did not actually alter the management of this patient, it can help to establish the disease distribution and guide the biopsy.