ARRS Case of the Week- Dec 4, 2017

ULTRASOUND: Abdomen

Case Author: Ulrike M. Hamper, MD, MBA, John Hopkins University

History

87-year-old man with right upper quadrant discomfort and hypoglycemia.

Imaging Findings

Sagittal (A) and transverse (B) gray-scale ultrasound images of the pancreas show a 1.4 × 1.1 × 1.3 cm hypoechoic mass (calipers) in the pancreatic head just medial to a small cyst and anterior to the splenic vein. Transverse (C) and sagittal (D) color Doppler ultrasound images show peripheral blood flow but no internal vascularity of the mass.

Insulinoma
Intraductal papillary mucinous neoplasm
Pancreatic adenocarcinoma
Pancreatic lymphoma

Diagnosis

Insulinoma

Teaching Points

Intraductal papillary mucinous neoplasm (IPMN) is usually found in older persons of either sex. IPMN communicates with ducts and is found more commonly in the head of the pancreas. Ultrasound or CT of IPMN typically reveals a cystic mass in the head of the pancreas that communicates with the pancreatic ductal system. IPMN progresses to invasive carcinoma in 35% of cases. Mucinous cystic neoplasm of the pancreas is the main entity to consider in the differential diagnosis. Pancreatic adenocarcinoma is more common in the head than body or tail of the pancreas and is seen as a poorly defined, homogeneous or heterogeneous hypoechoic mass in the pancreas or pancreatic bed. Dilatation of the pancreatic and common bile duct and atrophy of the gland proximal to the obstruction may be seen, as may venous invasion and encasement of the celiac axis and superior mesenteric artery. CT or MRI is more accurate for diagnosis and staging than is ultrasound. Insulinoma and gastrinoma account for 80% of hyperfunctioning pancreatic endocrine tumors, which constitute 1–5% of pancreatic neoplasms. Hyperfunctioning tumors tend to be small and malignant, with the exception of insulinomas. At ultrasound, hyperfunctioning pancreatic endocrine tumors are small (1–3 cm) round or oval hypoechoic masses with smooth margins. Intraoperative sonography is the most sensitive method of evaluating these small lesions and often is used to guide surgical treatment. Primary pancreatic lymphoma is a rare extranodal manifestation of any histopathologic subtype of B-cell non-Hodgkin lymphoma. Pancreatic lymphoma can also represent a direct extension from adjacent peripancreatic lymphadenopathy. At sonography one may see a focal hypoechoic masses or masses or diffuse infiltration of the gland.

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