Childhood familial pheochromocytoma. Conflicting results of localization techniques.

Childhood familial pheochromocytoma was investigated in four patients by abdominal computed tomographic scan, [131I]metaiodobenzylguanidine scan, and vena caval catecholamine sampling. Results conflicted with surgical findings. Computed tomographic scan identified all four adrenal tumors but missed two midline tumors in one patient. [131I]metaiodobenzylguanidine scan identified two of three adrenal tumors but also suggested extra-adrenal tumors not confirmed at operation in two of three patients. Vena caval sampling for catecholamines confirmed all adrenal tumors but suggested additional tumors not verified at operation in two of three patients. All patients are asymptomatic and have normal urinary catecholamines 15 to 51 months after operation. Because of the frequency of multiple tumors in familial pheochromocytoma, different diagnostic techniques were employed. False-positive results were more frequent with [131I]metaiodobenzylguanidine and vena caval sampling. Reinterpretation of the [131I]metaiodobenzylguanidine scans at a later date led to less false-positive interpretation, although the false-negative rate remained unchanged. More pediatric experience with [131I]metaiodobenzylguanidine scans and vena caval sampling in familial pheochromocytoma is needed. Confirmation of tumor and its localization rest with meticulous surgical exploration.