Pancreatic ductal adenocarcinoma with intratumoral cystic lesions on MRI: correlation with histopathological findings

Abstract

The purpose of this study was to evaluate intratumoral cystic lesions of pancreatic ductal adenocarcinoma (PDAC) depicted on MRI, and to correlate these cystic lesions with their histopathological findings. This study included 12 patients (7 males and 5 females; mean age, 59 years) with intratumoral cystic lesions of PDAC detected on a retrospective MRI review. We reviewed the histopathological findings of the cystic lesions within PDACs and analysed the MRI findings, focusing on the appearance of the intratumoral cystic lesions, i.e. the size, number, margin and intratumoral location, and on the ancillary findings of PDAC, i.e. peripancreatic infiltration, upstream pancreatic duct dilatation and distal parenchymal atrophy. Intratumoral cystic lesions were classified as neoplastic mucin cysts (n = 7, 58%) or cystic necrosis (n = 5, 42%) according to the histopathological findings; they ranged in greatest dimension from 0.5 cm to 3.4 cm (mean, 1.7 cm). Seven patients had only one cystic lesion each, while the remaining five had multiple cystic lesions. Most of the neoplastic mucin cysts had smooth margins (n = 6, 86%) and eccentric locations (n = 6), whereas most cystic necroses had irregular margins (n = 4, 80%) and centric locations (n = 4). The most common ancillary findings of PDAC were peripancreatic infiltration, distal pancreatic atrophy and upstream pancreatic duct dilatation (92%, 75% and 58%, respectively). The intratumoral cystic lesions of PDACs on MRI were classified as either neoplastic mucin cysts with smooth margins and eccentric locations or cystic necroses with irregular margins and centric locations.

Figure 1

A 59-year-old woman with pancreatic ductal adenocarcinoma (PDAC) and an intratumoral neoplastic mucin cyst in the pancreatic body (Case 1). (a) Axial contrast-enhanced CT scan shows a low-attenuation mass (arrowheads) containing an eccentric cyst (arrow) with upstream ductal dilatation (open arrow). (b) Axial contrast-enhanced fat-suppressed T₁ weighted fast-low angle shot (FLASH) image (repetition time/echo time (TR/TE), 149/4.1 ms; flip angle, 80°) shows a slightly hypointense mass (arrowheads) in the background of the more enhanced pancreatic parenchyma. Note the markedly hypointense lesion with a smooth margin, representing an intratumoral cyst (arrow), as well as the upstream ductal dilatation (open arrow). (c) Axial fat-suppressed T₂ weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) image (TR/TE, 4.4/134 ms; flip angle, 150°) shows an intratumoral cyst (arrow) with a smooth margin and bright signal intensity similar to that of the cerebrospinal fluid, as well as upstream ductal dilatation (open arrow). (d) Photograph of a surgical specimen shows a yellowish-gray infiltrative mass (open arrowheads) and an eccentrically located mucoid cystic change (asterisk). (e, f) Photomicrographs of a histological specimen show a cyst (asterisks) lined by mucin-secreting malignant cells (arrowheads in (f)) within the fibrous stroma of an ordinary PDAC (haematoxylin and eosin stain, ×10 (e) and ×200 (f)).

Figure 2

A 51-year-old man with pancreatic ductal adenocarcinoma and intratumoral neoplastic mucin cysts in the pancreatic tail (Case 4). (a) Axial contrast-enhanced fat-suppressed T₁ weighted fast-low angle shot (FLASH) image shows two eccentrically located cysts (arrows) surrounded by a peripheral, irregular, rim-like enhancing mass (arrowheads). Note the infiltration of the peripancreatic fat planes (open arrows). (b) Axial fat-suppressed T₂ weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) image shows three eccentrically located cysts with smooth margins (arrows). (c) Thick-slab coronal oblique MR cholangiopancreatography image with single-shot rapid acquisition with relaxation enhancement (RARE) shows a cyst (arrows). Note that there is no dilatation of the downstream main pancreatic duct. (d) Photograph of a surgical specimen shows an ill-defined, greyish to yellowish, firm mass (open arrowheads) with two eccentrically located cystic lesions (asterisks). (e) Photomicrograph of a histological specimen shows a cyst (asterisk) lined by mucin-producing neoplastic cells (arrowheads) (haematoxylin and eosin stain, ×100).

Figure 3

A 44-year-old man with pancreatic ductal adenocarcinoma and intratumoral cystic necroses in the pancreatic tail (Case 11). (a) An axial contrast-enhanced fat-suppressed T₁ weighted fast-low angle shot (FLASH) image and (b) an axial fat-suppressed T₂ weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) image show a relatively well-demarcated solid and cystic mass surrounded by irregular rim enhancement (arrowheads). The four irregularly marginated, cystic lesions are located in the centric and eccentric, i.e. combined, portions within the tumour (arrows). Note that the tumour invades the splenic hilum and produces ischaemic change in the spleen (open arrows). (c) Surgical specimen shows an inhomogeneously yellowish-white mass (open arrowheads) with multifocal necroses (asterisks).

Figure 4

A 58-year-old woman with pancreatic ductal adenocarcinoma and intratumoral cystic necroses in the pancreatic head (Case 12). (a) An axial contrast-enhanced fat-suppressed T₁ weighted fast low angle shot (FLASH) image and (b) an axial fat suppressed T₂ weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) image show a relatively large well-demarcated solid mass (arrowheads) with an irregularly marginated central area of necrosis (arrows). The mass laterally displaces the second portion of the duodenum (open arrows). The mass is accompanied by minimal dilatation of the common bile duct (open arrowhead in (b)) and of the main pancreatic duct (not shown).