inflammatorischer Pankreaspseudotumor
Mass-forming
pancreatitis versus pancreatic ductal adenocarcinoma: CT and MR imaging for differentiation. MFCP of the head in a 52 year-old male patient. a Axial and b coronal MDCT images demonstrate a hypoattuatting mass in the pancreatic head (arrows) with subsequent dilatation of the pancreatic duct. There is a single small parenchymal calcification (arrowhead), which was not intraductally located according to multiplanar imaging. No other signs of CP are present. A confident diagnosis of MFCP cannot be made
Mass-forming
pancreatitis versus pancreatic ductal adenocarcinoma: CT and MR imaging for differentiation. MFCP of the tail (35 y, female). a Incidental note of an pancreatic tail mass (arrow) is made during CT angiography. There are multiple stippled calcification in the tail. b, c T1w GRE fatsat images show normal SI of the body and markedly low SI of the tail (arrow). d MRCP shows a stricture at the junction of pancreatic body and tail (arrow) and two fluid collections in the tail (arrowheads). e Gadolinium-enhanced image shows hypovascular mass and minimal ductal dilatation in the mass (arrow). The two small fluid collections adjacent to the pancreas are pseudocysts (arrowheads). Clues to the diagnosis of MFCP are lack of a duct-obstructing mass at the stricture at the junction of body and tail, presence of pseudocysts and parenchymal calcifications (at CT)
Mass-forming
pancreatitis versus pancreatic ductal adenocarcinoma: CT and MR imaging for differentiation. MFCP of the head (86 y, male). a T1w GRE fatsat, b T2w TSE, and c gadolinium-enhanced T1w GRE images show a mass in the head (arrows). The panc. duct traverses the mass (arrowheads) (duct-penetrating sign), which is typical for an inflammatory mass. d MRCP even better shows duct-penetrating sign (arrowhead). There are also typical signs of CP with ductal irregularities and dilated side branches throughout the gland
Mass-forming
pancreatitis versus pancreatic ductal adenocarcinoma: CT and MR imaging for differentiation. Calcified MFCP of the head (57 y, male). a, b Axial contrast-enhanced MDCT shows a hypoattenuating mass of the head with coarse calcifications (arrowheads) and a pancreatic plastic stent in place (arrow). The pancreatic duct is dilated. There are no signs of CP in the rest of the pancreas. c Paracoronal MDCT reformation demonstrates the stent (arrow) in the pancreatic head and the parenchymal calcifications (arrowheads) to better advantage
Mass-forming
pancreatitis versus pancreatic ductal adenocarcinoma: CT and MR imaging for differentiation. “False-positive” double duct sign in a patient with MFCP (67 y, female). a Axial MDCT shows severely atrophic pancreas with stippled calcifications in long-standing CP. b In the head there is a hypovascular mass, which causes c abrupt cut-off (arows) of common bile duct and main pancreatic duct (double duct sign), highly suspicious for PDAC developing in CP. d ADC shows only minimally restricted diffusion of the mass (arrows) (ADC value 1.51 × 10− 3 mm2/s), which is more in favour of inflammation. Patient underwent surgery, which revealed an inflammatory mass and no cancer
Focal
mass-forming chronic pancreatitis: indistinguishable from pancreatic carcinoma?. The mass (arrowheads) at dorsal aspect of pancreatic head showed loss of expected pancreatic enhancement in arterial-dominant acquisition (c,d) , without frank hypo- or hypervascularity and signs of vascular invasion.
Focal
mass-forming chronic pancreatitis: indistinguishable from pancreatic carcinoma?. The mass (arrowheads) at dorsal aspect of pancreatic head showed loss of expected pancreatic enhancement in arterial-dominant acquisition (c,d) , without frank hypo- or hypervascularity. Note mildly dilated CBD (1cm, thick arrow).
Focal
mass-forming chronic pancreatitis: indistinguishable from pancreatic carcinoma?. MRCP (without secretin administration) confirmed and depicted mild dilatation of left intrahepatic branches and CBD (thick arrow, 1 cm) plus dilated MPD (arrows) and side branches ("double-duct sign") above pancreatic head mass.
Mass-forming chronic pancreatitis occurs in around 30% of cases of chronic pancreatitis, where a mass or a focal enlargement of the pancreas is usually seen on imaging. In many instances, it poses a challenge as the epidemiology and imaging appearances overlap those of pancreatic adenocarcinoma.
Epidemiology
- ~ 30% of patients with chronic pancreatitis
- ~ 70% of mass-forming chronic pancreatitis manifest in the pancreatic head
Clinical presentation
Symptoms and risk factors tend to overlap with those of malignancy, including abdominal pain, weight loss, nausea, and jaundice .
Radiographic features
Generally, it manifests with a focal enlargement or a mass-like lesion of the pancreas, which is hypoenhancing . It may be associated with main pancreatic duct and common bile duct dilatation when localized at the pancreatic head, but they commonly taper smoothly and are not completely obstructed (cf. abrupt cutoff in pancreatic adenocarcinoma) - duct penetrating sign.
CT
- hypoattenuating and hypoenhancing
- features that help supporting an inflammatory process over malignancy :
MRI
- T1: hypo to isointense
- T2: iso to hyperintense
- C+ (Gd): variable pattern of enhancement on dynamic phases, usually with loss of the early/arterial phase pancreatic enhancement
Treatment and prognosis
Endoscopic ultrasound (EUS) and fine-needle aspiration (FNA) need to be considered in the equivocal imaging cases.
Studies have shown that ~5%-10% of resected pancreatic head carcinomas are confirmed to represent an inflammatory mass .
Differential diagnosis
- pancreatic adenocarcinoma
- peripheral displacement of chronic pancreatitis calcifications may suggest underlying malignancy
- double duct sign
- soft tissue encasement of adjacent vasculature
- autoimmune pancreatitis
- paraduodenal pancreatitis
- non-functioning pancreatic neuroendocrine tumor
- solid pseudopapillary tumor
- pancreatic metastasis
Siehe auch:
Assoziationen und Differentialdiagnosen zu inflammatorischer Pankreaspseudotumor:
