Key Data: Tumor Size and Intracellular Lipid Content Predict Risk of Adrenocortical Carcinoma

A brief summary of one of the key recent publications in assessment of adrenal lesions by Dr. Alexander Kutikov.

Risks of harboring adrenocortical carcinoma (ACC) dictate much of modern management of adrenal incidentaloma (AI). Tumor size and cross-sectional imaging features inform critical clinical decision-making regarding ACC risk.  In one of the largest series reported to date, AIs (n=2219) were either resected or monitored for at least 12 months between 2000 and 2017.  The following insights were gleaned:

• Overall, Adrenocortical carcinoma (ACC) incidence was 1.7%

• When ACC risk was assessed by tumor size: 

  • 0.1% in masses <4 cm 

  • 2.4% in masses 4-6 cm 

  • 19.5% in masses >6 cm 

• Proposed optimal size cut-off for ACC in AI = 4.6 cm based on these data. 

• When ACC risk was assessed by Hounsfield density:

  • 0% in masses <10 HU 

  • 0.5% in masses 10-20 HU

  • 6.3% in masses >20 HU 

• Proposed optimal density cut-off of 20 HU for diagnosis of ACC based on these data. 

Of note, 15.5% of all AIs and 19.2% of ACCs were hormonally active. 

As such, patients with smaller tumors (<4.6cm) that demonstrate lipid-rich features (<20HU) have a particularly low risk of harboring ACC. Patients should be counseled and selected for adrenalectomy based on these data. 

Kahramangil, B. et al. A Modern Assessment of Cancer Risk in Adrenal Incidentalomas. Ann Surg 275, e238–e244 (2020)