Anatomy of

Pancreas and

Congenital

Anomalies

OBJECTIVES• To explain about anatomy of pancreas:

– Gross : blood supply, lymphatic drainage, innervations, ducts system, embryology– Histology : exocrine, endocrine

• To explain about congenital anomalies of pancreas:1. Agenesis2. Pancreas Divisum3. Annular Pancreas4. Ectopic Pancreas5. Congenital Cysts

Anatomy of Pancreas

Gross Histology

GROSS ANATOMY OF PANCREAS• A gland with both exocrine and endocrine functions.• 15-25 cm long• 60-100 g• Location: retro-peritoneum, 2nd lumbar vertebral level• Extends in an oblique, transverse position• Parts of pancreas: head, neck, body and tail

BLOOD SUPPLIES & INNERVATIONS

Arterial Supply:– splenic artery– pancreaticoduodenal arteries

Venous Drainage: Suprapancreatic PV Retropancreatic PV Splenic vein Infrapancreatic SMV

• Ultimately, drains into portal vein

Innervations:• Sympathetic fibers (from the splanchnic nerves)• Parasympathetic fibers (from the vagus)

DUCTS OF PANCREAS

• The pancreatic duct begins in the tail of pancreas.• Joins CBD at the Ampulla of Vater.• 2 – 4 mm in diameter, 20 secondary branches• Lesser duct (Santorini) drains superior portion of head

and empties separately into 2nd portion of duodenum

• Has rich periacinar networks that drain into 5 nodal groups:– Superior nodes– Anterior nodes– Inferior nodes– Posterior PD nodes– Splenic nodes

LYMPHATIC DRAINAGE

HISTOLOGY OF PANCREAS

• Pancreatic acini + duct system.• Produces digestive enzymes

(amylase, trypsin, lipase) and alkaline fluid.

Exocrine Parts

Endocrine Parts

• Islets of Langerhans (pancreatic islets)

• Regulator of glucose, lipid, protein homeostasis.

• b cells at central– Produce insulin

• a cells peripheral– Produce glucagon

• g cells peripheral– Produce

somatostatin

ISLET OF LANGERHAN

NORMAL EMBRYOLOGY• The openings of two

ducts carried into line with each other.

• Two parts of the gland fuse to form one pancreas.

• Dorsal pancreatic duct becomes the accessory pancreatic duct.

• Duct of ventral bud forms the main pancreatic duct.

• Terminal parts of branching ducts form pancreatic acini.

NORMAL EMBRYOLOGY

CONGENITAL DISEASES

Agenesis •Highest mortality rate

Pancreas Divisum •Most common

Annular Pancreas

Ectopic Pancreas

Congenital Cysts

Agenesis• Characterized by:

– absence of a critical mass of pancreatic tissue or, in rare cases, totally absent.

• Cause:– Genetic mutation of PDX1 gene,

located on chromosomal locus 13q12.1

• Normal pancreatic development requires pancreatic duodenal homeobox 1, a homeodomain transcription factor.

• Severity depends on amount of functional pancreatic tissue present.

PANCREAS WITH ABSENT BODY AND TAIL

Associated disease:• Pancreaticobiliary duct anomalies – can lead to acute/chronic

pancreatitisSymptoms:• Abdominal pain• Diabetes (dorsal pancreas agenesis)• Lipid-rich stool (caused by defect of pancreatic enzymes)Exam and Tests:• Abdominal ultrasound• Abdominal CT scanManagement:• treatment of the diabetes and exocrine deficiency, when present. • Infusion of subcutaneous insulin, administration of pancreatic

enzyme.Prognosis:• Variable, depending on the quality of treatment received.

Pancreas Divisum• The duct systems of the

fetal pancreatic primordia fail to fuse.

• most common birth defect.• The cause of the defect is

unknown.• Many cases go undetected.• Pathogenesis:

– The ventral bud failed to fuse with dorsal bud during fetal development.

Clinical features: • Abdominal pain and swelling, nausea or vomiting.• Note: symptoms absent without pancreatitisExams and Tests:• Abdominal ultrasound• Abdominal CT scan• Amylase and lipase blood testTreatment:• Surgery.Complication:• PancreatitisPrognosis:• The outcome is usually good.

Annular Pancreas• A ring of pancreatic tissue

that completely encircles the duodenum.

• Pathogenesis:– May occur when the ventral bud

splits (become bifid), the two segments may encircle the duodenum .

ANNULAR PANCREAS

Annular Pancreas• Symptoms:

Newborns spit up more than normal, do not drink enough milk Adult fullness after eating, nausea or vomiting

• Symptoms occur when the ring of pancreas squeezes and narrows the small intestine.

• Conditions that may be associated with annular pancreas include:– Down syndrome– Excess amniotic fluid during pregnancy (polyhydramnios)– Other congenital gastrointestinal problems– Peritonitis

Exams and Tests:• Abdominal ultrasound• Abdominal x-rayTreatment:• Surgical bypass of the blocked part of the duodenum.Prognosis:• Good outcome with surgery.Complications:• Obstructive jaundice• Pancreatic cancer• Peptic ulcer• Perforation (tearing a hole) of the intestine due to obstruction

Annular Pancreas

Ectopic Pancreas• also known as heterotopic pancreatic tissue.• condition where pancreatic tissues lie outside and separate

to pancreatic gland. • Most are completely asymptomatic.• Common sites:

– Duodenum– Jejunum – Ileum– Meckel’s Diverticulum (remnant of yolk sac)

Symptoms:• Usually non-specific• Abnominal pain & dyspepsia

Diagnosis:• GI endoscopy

Complication:• Intestinal obstruction• Carcinoma of the ectopic pancreatic tissue

Treatment:• Surgery if symptomatic

Ectopic Pancreas

Congenital Cysts• Results from anomalous development of the

pancreatic ducts.• Morphology: – unilocular cysts, range from 5cm in diameter.– Lined by either uniform cuboidal or flattened

epithelium and are enclosed in a thin, fibrous capsule.

– Contains clear serous fluid – important point from pancreatic cystic neoplasms (which is mucinous)

CONGENITAL CYSTS

Symptoms:• Abdominal swelling• Palpable mass• Vomit

Exams and Tests:• Ultrasonography

Management:• Surgery

Congenital Cysts

SUMMARY• There are five congenital diseases, agenesis, pancreas

divisum, annular pancreas, ectopic pancreas, and congenital cysts.

• The most common is pancreas divisum.• Agenesis has the highest mortality rate.• All treatments are via surgery except in agenesis,

insulin infusion (and other pancreatic secretion components) is needed.

• Polyhydramnios can occur in annular pancreas cases.• Cancer mostly occurs in the head of pancreas.

REFERENCES• Textbook of Robbins Basic Pathology• Textbook of Gray’s Anatomy• www.healthline.com • www.medscape.com

QUESTIONS1

1. The following are congenital diseases of pancreasA. Congenital cystsB. Pancreatic divisumC. Heterotopic pancreatic tissueD. AgenesisE. Annular pancreas

TTTTTC. Other name for Ectopic Pancreas

QUESTIONS

2. Pancreas divisum is the most common congenital disease. T/F

1

T

QUESTIONS

3. Annular pancreas is the incomplete fusion of the ducts of pancreas during fetal development. T/F

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FPancreas divisum incomplete fusionAnnular pancreas encircling duodenum

QUESTIONS

4. Congenital cysts can be managed by cystectomy. T/F

1

T

QUESTIONS

5. Common sites for ectopic pancreas areA. JejunumB. Meckel’s diverticulumC. CaecumD. RectumE. Ileum

1

TTFFT

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