Agenesis of the Dorsal Pancreas

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Agenesis of the entire pancreas is incompatible with life.99 Hypoplasia or aplasia of the uncinal process has been reported in patients with intestinal nonrotation.100

Agenesis of the dorsal pancreas has been found more frequently, occasionally reported as part of the polysplenia syndrome.101 Patients with this anomaly often present with abdominal pain and symptoms of diabetes mellitus. Ultrasound or CT is usually diagnostic in revealing a round hypertrophied head of the pancreas without evidence of the body and tail of the pancreas102 (Fig. 2-54). The finding that there is no evidence of pancreatic duct in the region of the body and tail of the pancreas ventral to the splenic vein is important to differentiate it from pancreatic atrophy secondary to a proximally located pancreatic carcinoma.

Gemaciones Pancreaticas Dorsal Ventral

Fig. 2-46. Formation of the pancreas.

(a) Starting in the fourth week, the ventral pancreatic anlage rotates 180° (first to the right, and then posteriorly) as the duodenum rotates 90° as well. This results in a total rotation of 270°, with the original ventral anlage coming to the left of the duodenum. This rotation also carries the distal common bile duct posterior to the duodenum.

(b) The dorsal anlage is carried along by the duodenal rotation so that it too lies to the left of the duodenum.

(c) By the seventh to eighth week, the ducts of the two pancreatic buds fuse, with the ventral pancreas contributing the distal portion of the main pancreatic duct. Most of the proximal main duct arises from the dorsal anlage.

(From Javors BR, Sloves JH.4)

Fig. 2-46. Formation of the pancreas.

(a) Starting in the fourth week, the ventral pancreatic anlage rotates 180° (first to the right, and then posteriorly) as the duodenum rotates 90° as well. This results in a total rotation of 270°, with the original ventral anlage coming to the left of the duodenum. This rotation also carries the distal common bile duct posterior to the duodenum.

(b) The dorsal anlage is carried along by the duodenal rotation so that it too lies to the left of the duodenum.

(c) By the seventh to eighth week, the ducts of the two pancreatic buds fuse, with the ventral pancreas contributing the distal portion of the main pancreatic duct. Most of the proximal main duct arises from the dorsal anlage.

(From Javors BR, Sloves JH.4)

Ventral Anlage

Fig. 2-47. Distinction between the pancreatic anlagen.

(a) Transverse sonogram of the midabdomen shows differential fatty infiltration of the pancreas. Note that the posteroinferior pancreatic head and uncinate process, representing the embryologic ventral pancreas, are less echogenic than the remainder of the gland, which develops from the dorsal pancreatic bud.

(b) Schematic diagram shows the relative positions of the ventral and dorsal anlagen of the pancreas in relation to the major blood vessels of that region.

Fig. 2-47. Distinction between the pancreatic anlagen.

(a) Transverse sonogram of the midabdomen shows differential fatty infiltration of the pancreas. Note that the posteroinferior pancreatic head and uncinate process, representing the embryologic ventral pancreas, are less echogenic than the remainder of the gland, which develops from the dorsal pancreatic bud.

(b) Schematic diagram shows the relative positions of the ventral and dorsal anlagen of the pancreas in relation to the major blood vessels of that region.

Dorsal Pancreas

Fig. 2—48. Prominent lateral contour of the head of the pancreas (normal variant).

(a and b) Enhanced CT scans in a 35-year-old man show prominent lateral contours anteriorly and posteriorly (arrows) lateral to the gastroduodenal artery (curved arrows). D = duodenum; SMV = superior mesenteric vein.

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