Solid cystic tumour of pancreas.
There are many types of pancreatic neoplasms. The vast majority are exocrine type but there are also rarer endocrine type cancers which produce hormones .
The commonest type of pancreatic cancer is that arising from the small ducts of the pancreas (ductal-type adenocarcinoma or PDAC).
CYSTIC TUMOURS are rarer exocrine tumours that cause a cyst or fluid filled sac in the pancreas. The content of the cyst can be rather watery and this type of cystic tumour is called serous cystadenoma.There are three sub-types:
Serous microcystic adenoma(SMA), mainly in occur in the body-tail region and almost all in elderly women, consist of numerous small cysts around a central scar.
Serous oligocystic and ill-demarcated adenmoa (SOIA), mainly in head of pancreas and occur in both sexes, consist of a few relatively large cysts
Von Hippel-Lindau associated cystic neoplasms (VHL-CN). they arise at multiple sites and in advanced disease may merge and involve the entire pancreas and occur in both sexes.
The content of the cyst can be filled with mucin and this type of cystic tumour is called a mucinous cystadenocarcinoma. This type of tumour is malignant.
IPMTs ( intra ductal papillary mucinous tumours). These are cancers that arise from cells lining the main pancreatic duct.
Pancreatic neuroendocrine tumours (PNETs),. These tumours may arise from the endocrine cells in the islets of Langerhans in the pancreas (islet cell tumours) or so called neuroendocrine cells either in the pancreas or ampulla of Vater (carcinoid tumours) or the duodenum (gastrinomas)
Acinar cell carcinomas are those which arises from acinar cells at the ends of the ducts that produce the pancreatic juices.
Papillary tumours: Solid and papillary neoplasms are rare, benign or low-grade malignant tumors more commonly seen in girls and young women .
Lymphoma in pancreas is extremely uncommon.
IMAGING:
Serous tumours are benign and typically contain greater than six cysts which are smaller than 20 mm and have a central stellate scar. On unenhanced CT, serous adenomas appear as hypodense masses that frequently show central calcification. In addition, a characteristic central fibrotic scar may be appreciated on contrast enhanced CT scan. On MR, it appears as a well-defined cystic lesion that does not show invasion of fat or adjacent organs. On T2 weighted images, the small cysts and intervening septations may appear like a cluster of small grape-like hyperintense cysts, post-contrast MRI shows minimal enhancement of tumour septae.
Mucinous cystic neoplasms are most often located in the body or tail of the pancreas. They reveal cysts that are less numerous and larger in size (average diameter=12 cm) than are typically observed with serous cystadenoma. On CT, they appear as round to ovoid, externally smooth, near-water-density cystic lesions. Amorphous calcification, septations and solid excrescences may be seen. CECT demonstrates the enhancement of cystic walls and thin, straight or curvilinear septations. Higher inherent soft-tissue contrast of MRI allows better differentiation between serous and mucinous cystadenomas. Mucin produced by these tumours may result in high signal intensity on T1 weighted and T2 weighted images of the primary tumour. Thick irregular septae and solid portions or papillary excrescences may be seen on gadolinium enhanced T1 weighted fat-suppressed images or contrast enhanced CT in patients with mucinous cystadenocarcinoma. Mucinous cystadenoma and cystadenocarcinoma do not have central scars.
Intraductal papillary mucinous tumour (IPMT). It is characterized by the presence of cystic dilation of the branches of the pancreatic duct in the uncinate process, diffuse or segmental dilatation of the main pancreatic duct(main duct type), or dilatation of the main duct and the branch ducts (combined type). Intraductal fungating lesions or mucin deposits may cause small intraductal areas with solid signal intensity seen on MRI. MRCP can demonstrate the dilated ducts as hyperintense collections. The branch duct mucinous tumour is characterized by cystic ectasia of the branch ducts, forming a mass with lobulated contours that usually involves the uncinateprocess. MRCP may demonstrate a grape-like appearance of the lesion and its wide communication with the main pancreatic duct .
Pancreatic neuroendocrine tumours
Insulinomas and gastrinomas are the most common functioning islet cell tumours and are generally small at the time of detection. Other functioning and non-functioning pancreatic neuroendocrine tumours such asglucagonomas, somatostatinomas, VIPomas (secreting vasoactive intestinal polypeptide) and GRFomas (secreting growth hormone-releasing factor) are frequently large at diagnosis and are often malignant.
Insulinomas and gastrinomas are the most common functioning islet cell tumours and are generally small at the time of detection. Other functioning and non-functioning pancreatic neuroendocrine tumours such asglucagonomas, somatostatinomas, VIPomas (secreting vasoactive intestinal polypeptide) and GRFomas (secreting growth hormone-releasing factor) are frequently large at diagnosis and are often malignant.
Functioning neuroendocrine tumours
These tumours are hypervascular and are best detected in the arterial phase with thin slices. Typically they are usually isolated to the \"gastrinoma triangle\" whose vertices are the cystic duct confluence, the junction of the pancreatic neck and body, and the junction of the second and third portions of duodenum On T1 weighted fat suppressed images, these lesions are hypointense to pancreatic parenchyma.Due to the longer relaxation time, these tumours exhibit high signal intensity relative to the normal pancreas on T2 weighted images, facilitating the detection of small tumours. Being hypervascular, these tumours frequently demonstrate homogeneous or ring enhancement during the arterial phase of contrast enhanced dynamic MR imaging.
These tumours are hypervascular and are best detected in the arterial phase with thin slices. Typically they are usually isolated to the \"gastrinoma triangle\" whose vertices are the cystic duct confluence, the junction of the pancreatic neck and body, and the junction of the second and third portions of duodenum On T1 weighted fat suppressed images, these lesions are hypointense to pancreatic parenchyma.Due to the longer relaxation time, these tumours exhibit high signal intensity relative to the normal pancreas on T2 weighted images, facilitating the detection of small tumours. Being hypervascular, these tumours frequently demonstrate homogeneous or ring enhancement during the arterial phase of contrast enhanced dynamic MR imaging.