Pancreatic true cyst is a rare congenital cystic lesion lined by epithelium. Unlike pseudocysts, it has a true epithelial wall structure. It is usually incidentally detected and asymptomatic. Its association with Von Hippel-Lindau (VHL) disease, autosomal dominant polycystic kidney disease (ADPKD), and cystic fibrosis (CF) is well established. The sporadic isolated form is very rare. It meets simple cyst criteria: thin wall, no internal septa or solid components, no enhancement. There is no risk of malignant transformation and treatment is generally not required.
Age Range
20-70
Peak Age
-
Gender
Equal
Prevalence
Rare
Pancreatic true cysts arise from anomalies in embryonal pancreatic duct development. During pancreatic duct system development, some ductal segments become isolated, forming closed spaces lined by epithelium. These cysts are lined by cuboidal or flat epithelium that secretes serous fluid. In VHL disease, VHL tumor suppressor gene mutation triggers pancreatic cyst formation — pancreatic cysts are found in 35-70% of VHL patients. In ADPKD, polycystin gene mutation leads to cyst formation in multiple organs (kidney, liver, pancreas). In cystic fibrosis, thick mucinous secretions cause pancreatic duct obstruction and secondary cyst formation. The reason it meets simple cyst criteria: thin wall (atrophic epithelium + thin fibrous capsule), absence of internal septa (unilocular cavity), no enhancement (avascular wall), homogeneous fluid content (serous fluid, no hemorrhagic or mucinous component).
Pancreatic cystic lesion meeting all simple cyst criteria: markedly T2 hyperintense similar to CSF, homogeneously T1 hypointense, no enhancement, no septa, no solid component, no mural nodule. In the absence of pancreatitis history, the diagnosis of true cyst can be confidently made. Presence of VHL/ADPKD/CF with multiple pancreatic cysts strengthens the diagnosis.
On non-contrast CT, a well-defined, round/oval cystic lesion with water attenuation (0-20 HU) is identified. The wall is very thin and usually not separately visible. No internal debris, hemorrhage, or calcification is present.
Report Sentence
A thin-walled, unilocular cystic lesion with water attenuation (XX HU) is identified in the pancreas, meeting simple cyst criteria.
On contrast-enhanced CT, no enhancement of the cyst wall is observed. Cyst contents remain at the same attenuation as the non-contrast phase. No septa, mural nodule, or solid component is present. These findings support the diagnosis of simple cyst.
Report Sentence
No enhancement of the cyst wall is observed on contrast-enhanced phases, consistent with simple cyst.
On T2-weighted MRI, the true cyst shows markedly hyperintense signal — bright signal similar to CSF. A thin smooth wall may be visible as a hypointense ring. No internal debris, septa, or fluid-fluid level is present. T2 signal intensity confirms simple fluid (serous) character.
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Markedly hyperintense signal similar to CSF is observed in the lesion on T2-weighted sequences, consistent with simple fluid content.
On T1-weighted MRI, the true cyst shows hypointense signal — reflecting simple fluid character. Presence of hyperintense signal suggests hemorrhagic or proteinaceous content and questions the simple cyst diagnosis.
Report Sentence
Hypointense signal is observed in the lesion on T1-weighted sequences, consistent with simple fluid content.
On ultrasonography, the true cyst appears as an anechoic, thin-walled, well-defined cystic lesion. Posterior acoustic enhancement is characteristic. No internal echoes, septa, or solid components are present. No vascularity is observed in the cyst wall on Doppler.
Report Sentence
An anechoic, thin-walled cystic lesion with posterior acoustic enhancement is identified in the pancreas, consistent with simple cyst.
On DWI, the true cyst shows no diffusion restriction — mild high signal on DWI may be seen due to T2 shine-through effect, but high signal on ADC map (no restriction) is diagnostic. Presence of diffusion restriction suggests abscess or highly proteinaceous cyst.
Report Sentence
No diffusion restriction is observed in the lesion on DWI, supporting the diagnosis of simple cyst.
Criteria
VHL disease diagnosis, usually multiple pancreatic cysts, bilateral renal cysts/tumors may coexist
Distinct Features
Pancreatic cysts found in 35-70% of VHL patients. Usually asymptomatic. May coexist with serous cystadenoma. Association with pNET (10-17%) possible — therefore all pancreatic lesions in VHL must be carefully evaluated.
Criteria
ADPKD diagnosis (bilateral renal cysts), multiple organ cysts (liver, pancreas)
Distinct Features
Pancreatic cysts in 10-15% of ADPKD patients. Usually a few small cysts. Liver cysts are also common. No malignancy risk — follow-up only if size increase or symptoms.
Criteria
No underlying syndrome, isolated solitary pancreatic cyst, simple cyst criteria
Distinct Features
Very rare. Careful exclusion of other cystic neoplasms (IPMN, MCN, SCN) is required. Endoscopic US-guided cyst aspiration and fluid analysis (low CEA, low amylase) supports the diagnosis.
Criteria
Cystic fibrosis diagnosis, pancreatic cysts usually in the background of diffuse lipomatous change
Distinct Features
In CF, the pancreas usually shows diffuse fatty replacement (exocrine insufficiency). Small retention cysts form secondary to duct obstruction. Macrocysts are rarer. Pancreatic calcifications may coexist.
Distinguishing Feature
Pseudocyst is directly associated with pancreatitis history (acute or chronic) — true cyst is not related to pancreatitis. Pseudocyst wall is thicker (fibrous capsule) and may show enhancement. Pseudocyst may have irregular shape while true cyst is round/oval. Pseudocyst fluid contains high amylase.
Distinguishing Feature
Serous cystadenoma shows microcystic ('honeycomb') or oligocystic pattern — true cyst is unilocular. SCN has central calcified scar (30%) and septae show enhancement — true cyst has no septa and no enhancement. SCN typically occurs in elderly women.
Distinguishing Feature
Branch-duct IPMN is a cystic lesion communicating with the pancreatic duct — ductal communication is demonstrated on MRCP. IPMN may show mural nodule and enhancing septa. True cyst has no ductal communication and shows no enhancement. Elevated CEA in cyst fluid supports IPMN.
Distinguishing Feature
MCN occurs almost exclusively in women, in the pancreatic body/tail. MCN shows thick wall, peripheral calcification ('eggshell'), enhancing septa — true cyst lacks these. MCN has premalignant/malignant potential. MCN does not communicate with the duct.
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
no-follow-upPancreatic true cyst is benign with no risk of malignant transformation and requires no treatment. Small (<2 cm) lesions fully meeting simple cyst criteria do not require follow-up. In cases of diagnostic uncertainty (atypical features, solitary cyst, no syndromic association), EUS-guided aspiration and cyst fluid analysis (low CEA, low amylase, benign cytology) establishes the diagnosis. In VHL patients, the presence of pNET should also be screened alongside pancreatic cysts. Drainage or surgery is rarely needed for large symptomatic cysts (duct compression, pain).
Pancreatic true cysts are benign and require no treatment. However, differential diagnosis among cystic lesions in the pancreas is important because mucinous cystic neoplasm and IPMN have malignant potential. EUS-FNA and cyst fluid analysis are performed in doubtful cases.