Small intestine & ampulla

• Classical mutational profile in JPS involves either the bone morphogenetic protein receptor 1A (BMPR1A), located at 10q23 or SMAD4 gene, located at 18q21 (Clin Genet 2009;75:79, Gut 2008;57:623)
• Juvenile polyposis of infancy shows contiguous deletion of BMPR1A and PTEN genes at chromosome 10q23 (Am J Hum Genet 2006;78:1066)
• Neoplasia may arise in JPS from adenomatous epithelium within the polyp through a landscaper mechanism and abnormal stromal environment that affects TGFβ signaling (Science 1998;280:1036)
• Pathophysiology and etiology of sporadic / solitary juvenile polyps in small bowel is unknown

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• Genetic testing of the following gene mutations
  • SMAD4 and BMPR1A: for juvenile polyposis syndrome
  • PTEN: identified in juvenile polyposis of infancy and Cowden syndrome
  • STK11 / LKB1: seen in Peutz-Jeghers syndrome
• Preferred for at risk patients, starting at age of 4 (Curr Mol Med 2007;7:29)
• Upper and lower endoscopy surveillance starting at age 12 if symptomatic (Dis Colon Rectum 2012;55:1038)

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Contributed by Milton Smith, M.D.

Contributed by Divya Sharma, M.D., Rachel Sheridan, M.D. and Sara Szabo, M.D.

Upper esophagogastroduodenoscopy (EGD) in a 12 year old patient with history of abdominal pain and nausea showed multiple polyps in the second part of the duodenum. The largest polyp was biopsied and the microscopic findings demonstrated surface erosion and cystically dilated glands. Which of the following is a criterion for a diagnosis of juvenile polyposis syndrome (JPS) in this patient?

1. 2 colon polyps from the same patient with similar morphology to the duodenal polyp
2. Germline mutation in STK11 gene
3. Multiple duodenal polyps that are at least 10 mm in size
4. Positive family history

D. Positive family history. The biopsy findings show a polyp with features suggestive of a juvenile polyp (eroded surface, inflammatory stroma and dilated glands). A diagnosis of JPS requires one of the following criteria

• More than 3 - 5 juvenile polyps in colon or rectum
• Multiple juvenile polyps throughout gastrointestinal tract (including stomach and small intestine)
• Any number of juvenile polyps and positive family history

Answer B is incorrect as STK11 mutations are seen in Peutz-Jeghers syndrome. Answer A is incorrect because the diagnostic criteria of JPS requires the presence of more than 3 - 5 colorectal polyps. Answer C is incorrect as there is no polyp size cut off criteria for the diagnosis of JPS.

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Reference: Juvenile polyposis

The microscopic image above is from a biopsy of a duodenal polyp. Which of the following features, if present, favors a diagnosis of juvenile polyp over an inflammatory polyp?

1. Clinical history of inflammatory bowel disease
2. Hyperplasia of the glands with gland branching and cystic dilatation
3. Reactive atypia of the mucosal glands
4. Solitary polyp and mucosal hyperemia seen on esophagogastroduodenoscopy (EGD)

B. Hyperplasia of the glands with gland branching and cystic dilatation. These features are generally nonspecific; however, they are less likely to be seen in inflammatory polyps. Answer C is incorrect because reactive atypia in the glands can be seen in both juvenile and inflammatory polyps. Answers A and D are incorrect as these features favor a diagnosis of an inflammatory polyp.

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Reference: Juvenile polyposis