IMAGING

Changing role of imaging-guided percutaneous biopsy of adrenal masses: evaluation of 50 adrenal biopsies
Paulsen SD, Nghiem HV, Korobkin M, Caoili EM, Higgins EJ.
Department of Radiology, University of Michigan, 1500 E Medical Center Dr., UH B1 D530, Ann Arbor, MI, USA
AJR Am J Roentgenol. 2004; 182: 1033-7

• Objective: Prior series of percutaneous imaging-guided biopsies of adrenal masses before the advent of dedicated CT and MRI of the adrenal glands have shown that 40-57% of adrenal masses biopsied were adenomas-benign lesions requiring no further evaluation or treatment. This study was performed to assess the effect of dedicated adrenal imaging with CT and MRI on the rate of percutaneous imaging-guided biopsies of adrenal masses.
• Materials and Methods: We reviewed 50 consecutive adrenal mass biopsies performed during a 48-month period. The patient demographics, technique of biopsy, pathology results, and results of any prior dedicated adrenal imaging with MRI or CT protocols were noted.
• Results: Only six (12%) of 50 biopsies were adenomas. Five of these six cases were preceded by dedicated adrenal CT or MRI. Thirty-five cases were metastatic disease, four were adrenal cortical carcinoma, three were pheochromocytoma, and two biopsies were nondiagnostic. Overall, 20 of 50 cases were preceded by a dedicated adrenal CT or MRI examination to exclude an adenoma; in 21 of the remaining 30 cases, the imaging characteristics before biopsy were inconsistent with the potential diagnosis of an adenoma and dedicated adrenal CT or MRI was not recommended.
• Conclusion: The number of adrenal adenomas biopsied has declined markedly with the introduction of dedicated adrenal CT and MRI for adrenal adenomas. Percutaneous imaging-guided biopsy is useful in confirming the presence and nature of suspected metastatic deposits to the adrenal gland and in diagnosing or excluding adrenal adenomas in patients with equivocal imaging characteristics.
  
  
• Editorial Comment
  Most incidentally found adrenal masses are adenomas even in patients with known primary tumors.For this reason a well stablished radiologic work-up is currently used in this clinical setting. By using a dedicated adrenal radiologic evaluation(CT without contrast, washout-CT and chemical shift imaging by magnetic resonance), nearly all adrenal masses can be correctly categorized as adenomas or non-adenomas.Thus, percutaneous adrenal biopsy may be indicated for the small percentage of lesions that remain indeterminate in nature after CT and MRI. Such lesions include those with a percentage of wash-out near 60% threshold or lesions that have increased in size at follow-up imaging in spite of their benign appearance at prior CT study. As shown in this publication the number of adrenal masses biopsied has significantly reduced and consequently the number of adrenal adenomas. For the same reason the number of unnecessary ressection of adrenal incidentalomas has also declined.

Dr. Adilson Prando
Department of Radiology
Vera Cruz Hospital
Campinas, São Paulo, Brazil