Diagnostic Approach for Cysts

Initial Diagnostic Approach

The American College of Radiology recommends ultrasound as the first diagnostic test for suspected cysts, particularly for hepatic cysts, as it can reliably identify simple cysts with their characteristic features: anechoic appearance, sharp and smooth borders, thin walls, and strong acoustic posterior enhancement 2, 3
For pancreatic cysts, the American College of Radiology prefers contrast-enhanced MRI with MRCP over CT due to its superior soft-tissue resolution and ability to demonstrate ductal communication 4, 5
The National Comprehensive Cancer Network recommends ultrasound as the initial diagnostic imaging for breast cysts, especially for women younger than 30 years presenting with a dominant mass 6

Simple cysts appear as anechoic, well-circumscribed, round or oval with well-defined imperceptible wall and posterior enhancement on ultrasound, and typically follow an indolent course without significant changes in size over time 2, 3, 6, 7
Complex cysts have discrete solid components, which may include thick walls, thick septa, and/or intracystic masses, and carry a higher risk of malignancy 6, 7

MRI is superior to CT for characterizing cysts, particularly for pancreatic cysts, with a diagnostic accuracy of 73.2% to 91% for distinguishing between malignant and nonmalignant lesions 4, 5
For hepatic cysts, MRI is particularly useful for diagnosing cyst hemorrhage, showing heterogeneous hyperintensity on both T1- and T2-weighted sequences 1
CT is less accurate than MRI for cyst characterization but may be used when MRI is contraindicated, and can provide critical diagnostic information about calcifications, ductal dilation, septations, and mural nodules for pancreatic cysts 4, 8

Infected cysts can be diagnosed based on criteria including cyst aspiration showing evidence of infection, fever, CT/MRI detecting gas in a cyst, increased FDG activity on PET-CT, tenderness in the affected area, increased CRP, increased leukocyte count, and positive blood culture 1
Hemorrhagic cysts can be diagnosed using ultrasound, which may show sediment or mobile septations, and MRI, which shows heterogeneous and intense signal on both T1- and T2-weighted sequences 1

The presence of "worrisome features" or "high-risk stigmata" in pancreatic cysts significantly increases malignancy risk and should prompt further evaluation, according to the American College of Radiology 4
Complex breast cysts have a relatively high risk of malignancy (14-23%) and should be evaluated by tissue biopsy, as recommended by the National Comprehensive Cancer Network 7
Serum tumor markers like CEA and CA19-9 cannot reliably distinguish between simple hepatic cysts and mucinous cystic neoplasms of the liver, as stated by the Journal of Hepatology 3