6-iodomethylcholesterol and Pheochromocytoma

We reviewed the findings of adrenocortical scintigraphy with 131I-6-beta-iodomethyl-19-norcholesterol (NCL-6-131I) of 39 patients to clarify its role in the evaluation of unilateral adrenal or juxtaadrenal masses incidentally discovered by CT, ultrasonography or plain radiography. Twenty-seven benign adrenal masses showed various scintigraphic findings (hot nodule: 12 silent adenomas, warm nodule: one solid mass, normal appearance: one cyst and 2 solid masses, diffuse decrease: each one; solid mass, myelolipoma, ganglioneuroma and calcified adrenal and partial or complete defect: each one; solid mass, myelolipoma and ganglioneuroma and 2 cysts and 2 pheochromocytomas); while a partial or complete defect was shown in a nonfunctioning carcinoma and 3 metastases and a complete defect or inhomogeneous uptake without opposite adrenal visualization was shown in 2 patients with cortisol-producing carcinoma. Therefore a hot nodule and an inhomogeneous uptake or complete defect with nonvisualization of the opposite adrenal are specific to a benign tumor and a cortisol-producing carcinoma, respectively. The impaired tumor uptake of NCL-6-131I is a nonspecific finding. The scintigraphic findings of juxtaadrenal masses were normal in 4 and deviated adrenals in 2. Thus adrenocortical scintigraphy can identify silent adenomas and cortisol-producing carcinomas among the adrenal masses and may help to differentiate juxtaadrenal from adrenal masses.

Topics: 19-Iodocholesterol; Adenoma; Adrenal Gland Neoplasms; Adrenocortical Adenoma; Adult; Carcinoma, Renal Cell; Female; Ganglioneuroma; Humans; Male; Middle Aged; Myelolipoma; Neurilemmoma; Pheochromocytoma; Radionuclide Imaging; Tomography, X-Ray Computed; Ultrasonography

The exact localization of adrenal lesions can be achieved by noninvasive procedures. Whereas radiological methods reflect morphological changes, scintigraphy of adrenal cortex and medulla depends on function. - Radiolabeled 6 beta-methyl-19-norcholesterol is used for adrenocortical scintigraphy in primary aldosteronism, Cushing's syndrome and hyperandrogenism. By dexamethasone suppression a correct classification of adrenocortical lesions by scintigraphy can be observed in about 89% with a specificity of 86%. 123-I- and 131-I-metaiodobenzylguanidine is used for specific scintigraphy of the adrenal medulla. This method is a safe and reliable method for localization of adrenal and extraadrenal pheochromocytomas.

Topics: 19-Iodocholesterol; 3-Iodobenzylguanidine; Adrenal Gland Diseases; Adrenal Gland Neoplasms; Cholesterol; Cushing Syndrome; Dexamethasone; Humans; Hyperaldosteronism; Iodobenzenes; Pheochromocytoma; Radionuclide Imaging; Selenium; Succimer; Technetium; Technetium Tc 99m Dimercaptosuccinic Acid