Lipomatous Pseudohypertrophy of the Pancreas Taking the Form of Huge Massive Lesion of the Pancreatic Head

Abstract

A 70-year-old woman presented with hypogastric pain. Computed tomography and magnetic resonance imaging revealed a retroperitoneal tumor 18.0 cm in diameter with fatty tissue density, ventrally compressing the pancreatic head. We suspected a well-differentiated liposarcoma compressing the pancreas. At laparotomy, the tumor mass was the size of an infant's head; its center was located in the area corresponding to the pancreatic uncus. It was continuous with the pancreatic parenchyma through a poorly demarcated border, and we resected as much of the tumor mass as possible while conserving the pancreatic capsule. Histopathological examination indicated lipomatous pseudohypertrophy of the pancreas with proliferation of mature fatty tissue as the main constituent. At the periphery, islands of acinar tissue were retained among the fatty infiltration, which also contained branches of the pancreatic duct and islets of Langerhans. Previous reports have stated that this disorder only causes fatty replacements throughout the pancreas or in the pancreatic body and tail; however, in this patient, imaging and macroscopic examination revealed no fatty replacements in the pancreatic body and tail. We report this case, which we consider extremely rare, along with a brief review of the literature.

Fig. 1

Abdominal CT. A mass with the same intensity as fat was recognized in the lower abdomen, protruding below the liver. The mass had a maximum diameter of about 18.0 cm. a Axial view. b Coronal view.

Fig. 2

MRI. The mass had high intensity on T1 imaging, and on T2 imaging it had a similar intensity to subcutaneous and intraperitoneal fat. Fat suppression eliminated the signals from the mass. a T2. b Fat suppression.

Fig. 3

Operative findings. The pancreatic uncus and head had been partially replaced by the mass and were thin, and the mass did not have clear borders.

Fig. 4

Histopathological findings. The operative specimen was yellow, soft, elastic, and lobulated, resembling adipose tissue (maximum diameters 18.0 × 11.0 × 6.0 cm), and weighed about 600 g (a). Proliferation of mature adipose tissue was seen throughout the mass. Islands of acinar tissue remained at the periphery of the tumor mass, and fine pancreatic ducts were present within the fatty tissue (b). Immunohistochemical staining of the specimen showed expression of chromogranin A in the islets of Langerhans (c), and cytokeratin 19 was detected in the epithelial cells of pancreatic ducts (d).