”Compared with benign tumors, malignant tumors were less frequently diagnosed incidentally (45.5% vs 86.7%), were larger (7 cm [range, 4-24.4 cm] vs 5 cm [range, 4-20 cm]), and had higher unenhanced computed tomographic (CT) attenuation (34.5 Hounsfield units [HU] [range, 14.1-75.5 HU] vs 11.5 HU [range, −110 to 71.3 HU]; P<.001). On multivariate analysis, older age at diagnosis, male sex, nonincidental mode of discovery, larger tumor size, and higher unenhanced CT attenuation were all found to be statistically significant predictors of malignancy.”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39.

“Pheochromocytomas were diagnosed in 22% of our cohort patients, with approximately half being discovered incidentally (54%). Thus, it is essential to biochemically exclude PHEO, especially in an adrenal mass with indeterminate imaging characteristics. The prevalence of PHEO in patients with incidentally discovered adrenal tumors of any size was previously reported to be 4.2%.”
Clinical, Biochemical, and Radiological Characteristics of a Single-Center Retrospective Cohort of 705 Large Adrenal Tumors
Nicole M. Iñiguez-Ariza et al.
Mayo Clin Proc Innov Qual Outcomes. 2018 Mar; 2(1): 30–39.

” In contrast to the approach taken by the ACR, the American Association of Clinical Endocrinologists and American Association of Endocrine Surgeons has taken a more conservative approach and recommend imaging evaluation 3 to 6 months after the initial diagnosis, and then annually for 1 to 2 years for all nodules less than 4 cm, even those with benign characteristics. The European Society of Endocrinology and the European Network for the Study of Adrenal Tumors has taken a simpler approach and recommend no further follow-up imaging for nodules less than 4 cm with a nonenhanced attenuation of less than 10 HU (ie, those that can be diagnosed as lipid-rich adenomas).”
Incidental Adrenal Nodules 
Daniel I. Glazer, Michael T. Corwin, William W. Mayo-Smith
Radiol Clin N Am 59 (2021) 591–601

“ In this outpatient population, the prevalence of unsuspectedpancreatic cysts identified on 16-MDCT was 2.6%. Cyst presence strongly correlated with increasing age and the Asian race.” 
Prevalence of Unsuspected Pancreatic Cysts on MDCT
Laffan TA, Horton KM, Fishman EK, Hruban RH 
AJR 2008;802-807

“Incidental pancreatic cysts (PCs) are commonly encountered in radiology practice. The prevalence rate of PCs is estimated at 2.5%. There is a 9% reported incidence on computed tomography (CT) and a 27% incidence on MR imaging. PCs are a heterogeneous group, including intraductal papillary mucinous neoplasm (IPMN), serous cystic neoplasm (SCN), and mucinous cystic neoplasm (MCN). Non-neoplastic PCs are pancreatic pseudocysts (common), epithelial cysts (uncommon), and lymphoepithelial cysts (rare). The significance in categorizing PCs lies in the potential of the mucinous varieties to develop malignancy.” 
Incidental Pancreatic Cysts on Cross-Sectional Imaging 
Shannon M. Navarro et al.
Radiol Clin N Am 59 (2021) 617–629

Predictors of malignancy in IPMN include

• Lesion size (≥ 3cm)
• Interval growth over time (≥ 2mm/year)
• Mural nodule(s)
• Thick septations (enhancing)
• Clinical symptoms (including abdominal pain and unexplained episodes of pancreatitis)

• Aspiration is strongly advised to exclude pseudocyst before any surgery is performed
• Patients must remain asymptomatic during the follow-up period

Managing incidental findings on abdominal CT: white paper of the ACR incidental findings committee
Berland LL, Silverman SG, Gore RM et al.
J Am Coll Radiol 2010;7(10):754-73

“ The guidelines are as follows: Annual imaging surveillance is generally sufficient for benign serous cystadenomas smaller than 4 cm and for asymptomatic lesions. Asymptomatic thin-walled unilocular cystic lesions smaller than 3 cm or side-branch intraductal papillary mucinous neoplasms should be followed with CT or MRI at 6 and 12 months interval after detection.”
Diagnosis and Management of Cystic Pancreatic Lesions
Sahani DV et al.
AJR 2013; 200:343-354

“ Cystic lesions with more complex features or with growth rates greater than 1cm/year should be followed more closely or recommended for resection if the patients condition allows surgery. Symptomatic cystic lesions, neoplasms with high malignant potential, and lesions larger than 3 cm should be referred for surgical evaluation. Endoscopic ultrasound with fine needle aspiration (FNA) biopsy can be used preoperatively to assess the risk of malignancy.”
Diagnosis and Management of Cystic Pancreatic Lesions
Sahani DV et al.
AJR 2013; 200:343-354

“Despite published guidance recommendations and reported awareness of them, fewer than half of follow-up recommendations for FCPL are consistent with the guidance and considerable variability persists among radiologists.”
Focal Cystic Pancreatic Lesion Follow-up Recommendations After Publication of ACR White Paper on Managing Incidental Findings 
Mark D. Bobbin et al.
J Am Coll Radiol. 2017 Jun;14(6):757-764

“Radiologists may favor providing follow-up recommendations that more closely reflect the management algorithm preferred by ordering providers rather than those provided by outside organizations.”
Focal Cystic Pancreatic Lesion Follow-up Recommendations After Publication of ACR White Paper on Managing Incidental Findings 
Mark D. Bobbin et al.
J Am Coll Radiol. 2017 Jun;14(6):757-764

”IPMNs are cystic neoplasms with variable degree of malignant potential. They may evolve into dysplasia or invasive carcinoma and are associated with a higher risk for the development of PDAC in the gland separate from the IPMN sites. The rate of progression increases with time. Low-risk IPMNs have an approximately 8% chance of progression, whereas higher risk IPMNs have an approximately 25% chance of progression to PDAC in 10 years. Even presumed low- risk BD-IPMNs may demonstrate growth after 5 years.”
Incidental Pancreatic Cysts on Cross-Sectional Imaging 
Shannon M. Navarro et al.
Radiol Clin N Am 59 (2021) 617–629 

2017 Revision

For most patients, we advocate 9- to 10-year follow- up, terminating at the age of 80 years For patients who are <65 years old at the time of initial cyst detection, a follow-up terminating at age 80 will exceed the 9- to 10-year length, but may be prudent ;such decisions regarding additional follow-up should be determined at the individual patient level.

Management of Incidental Pancreatic Cysts: A White Paper of the ACR Incidental Findings Committee.
Megibow AJ et al.
 J Am Coll Radiol. 2017 Jul;14(7):911-923.

Management of Incidental Pancreatic Cysts: A White Paper of the ACR Incidental Findings Committee.
Megibow AJ et al.
 J Am Coll Radiol. 2017 Jul;14(7):911-923.

Management of Incidental Pancreatic Cysts: A White Paper of the ACR Incidental Findings Committee.
Megibow AJ et al.
 J Am Coll Radiol. 2017 Jul;14(7):911-923.

Management of Incidental Pancreatic Cysts: A White Paper of the ACR Incidental Findings Committee.
Megibow AJ et al.
 J Am Coll Radiol. 2017 Jul;14(7):911-923.

Management of Incidental Pancreatic Cysts: A White Paper of the ACR Incidental Findings Committee.
Megibow AJ et al.
 J Am Coll Radiol. 2017 Jul;14(7):911-923.

“The natural history of incidental pancreatic cysts remains uncertain, and our recommendations cannot be simple or entirely definitive. Since 2010, several multi-institutional and specialty society consensus papers, meta-analyses, and large-scale observational studies have appeared but the quality of evidence has been characterized as poor or inconclusive, and conclusions remain controversial.” 
Management of Incidental Pancreatic Cysts: A White Paper of the ACR Incidental Findings Committee.
Megibow AJ et al. 
J Am Coll Radiol. 2017 Jul;14(7):911-923.