Functional imaging as an aid to decision-making in metastatic paraganglioma

Malignant paraganglioma is a rare and slow growing tumour of neuroendocrine origin. At the time of diagnosis, the tumour is usually widespread, with limited therapeutic options. A variety of functional imaging studies are available for staging the disease, guiding therapy and monitoring treatment response. These include I-123-MIBG or I-131-MIBG In-111-pentetreotide or In-111-lanreotide (somatostatin analogues), and F-18-FDG positron emission tomography. Various radionuclides, including I-131 and Y-90, can be targeted to the tumour using MIBG or pentetreotide. Such targeted radionuclide therapy may provide valuable long-term palliation in such patients. We present two cases with metastatic paragangliomas who had widespread soft tissue and bone metastases. One patient was treatment naive and the second had received previous chemotherapy. The functional imaging work-up performed and the targeted radionuclide therapies considered in these patients are described. Both patients were treated with I-131-MIBG. Partial tumour response and complete symptomatic and hormonal response was achieved in one patient: in the second patient there was no change.