Metastatic phaeochromocytoma with a long-term response after iodine-131 metaiodobenzylguanidine therapy.

Iodine-131 metaiodobenzylguanidine ([131I]MIBG), a radiopharmaceutical agent, is used for treating malignant phaeochromocytoma. [131I]MIBG therapy results in a hormone response rate of approximately 50%, but generally it yields only a partial or no tumour response. We present a case of a 46-year-old woman with a familial history of von Hippel-Lindau disease, who was treated with [131I]MIBG for a metastatic phaeochromocytoma involving the lungs, liver and bones. The patient received a cumulative dose of 33.3 GBq (900 mCi) and a complete hormone response was observed, as evaluated on the basis of catecholamine and metanephrine levels. Conventional radiography, computerized tomography and [131I]MIBG scintigraphy indicated that a near-complete tumour regression was achieved, with no evidence of relapse during a 4-year follow-up period. This case thus demonstrates that treatment with [131I]MIBG may lead to a dramatic tumour response in malignant phaeochromocytoma presenting both soft tissue and bone metastases.