Adrenal: Benign Tumours

Adenomas

• Most common primary adrenal tumour
• Incidence increases with age
• Diagnosis and Evaluation
  • Vast majority (93%) are metabolically silent
    • The essential evaluation of the small adrenal mass requires differentiating the nonfunctional benign adenoma from functional or malignant lesions
  • Imaging
  • Insert Image

CT scan demonstrating right adrenal adenoma

Source: Wikipedia

• Management
  • Functional adenoma
    • Should undergo resection in acceptable surgical candidate.
  • Non-functional adenoma
    • Size of lesion and its growth characteristics dictate management as described above
    • Adenomas that are initially metabolically inert are unlikely (<2%) to gain function.
      • Despite this low rate of “metabolic transformation,” the most recent consensus statement by a panel of NIH-convened experts suggests that annual metabolic hormonal screening for the first 3-4 years after diagnosis is prudent

Oncocytoma

• Extremely rare
• Despite predominantly benign lesions, a proportion of lesions can exhibit malignant potential
• On imaging, adrenal oncocytic lesions do not possess the central stellate scar often seen in renal oncocytomas
• Because the diagnosis of adrenal oncocytic tumor is nearly always made on surgical resection, the evaluation and treatment of oncocytic lesions follow the same strategy as that of other adrenal masses

Myelolipoma

• Rare, benign, metabolically silent lesions
• Possess tissue components identical to healthy bone marrow
• In the majority of cases, diagnosis of myelolipoma can be made accurately on cross-sectional imaging
  • Usual enhancement on CT is between -30 and -140 Hounsfield Units  
• The NIH consensus panel on adrenal incidentaloma concluded that myelolipoma can be regarded as an exception to the mandatory metabolic workup of a newly discovered adrenal mass
• Classically asymptomatic myelolipomas are treated conservatively; surgery is indicated only for extremely large or symptomatic lesions.

Genglioneuroma

• Extremely rare benign neuroectodermal neoplasms
• Tend to occur in the young and are composed of ganglion and Schwann cells
• Tumors can grow extremely large and have a propensity to encase vessels without impinging on the vessel lumen

Cysts

• 4 types of adrenal cysts have been described: pseudocysts, endothelial cysts, epithelial cysts, and parasitic cysts
• 7% of adrenal cysts are associated with malignancy, all of which were pseudocysts; because of the known chance of associated malignancy, observation of adrenal cysts must be done with caution
• Although the majority of adrenal cysts are benign and nonfunctional, routine endocrinologic evaluation should be performed to exclude active lesions

Questions

1. What is the histology of the most common primary adrenal tumour?

Answers

1. What is the histology of the most common primary adrenal tumour?
   1. Adenoma

References

• Wein AJ, Kavoussi LR, Partin AW, Peters CA (eds): CAMPBELL-WALSH UROLOGY, ed 11. Philadelphia, Elsevier, 2015, chap 65