Intraductal Tubular Adenoma of the Pancreas

Definition

• Cytologically bland nodular pancreatic intraductal epithelial proliferation with a predominantly tubular architecture

Alternate/Historical Names

• Intraductal tubular adenoma, pyloric gland type
• Intraductal tubular neoplasm with low grade dysplasia
• Pyloric gland adenoma of the pancreas

Diagnostic Criteria

• Nodular intraductal growth
  • Duct dilated locally
    • May fill and obliterate duct lining
    • Grossly present mucin but no distension of ducts
  • Upstream pancreas may be atrophic
• Tubular growth pattern predominates
  • Tightly packed tubules
  • Variable sized tubules
  • May be focally villous
• Cuboidal to columnar cells resembling normal pyloric gland cells
  • Moderate to abundant apical cytoplasm
    • Eosinophilic to clear cytoplasm
    • Abundant cytoplasmic mucin in most cases
  • Basal nuclei
  • Scattered goblet cells and endocrine cells may be present
• Cytologically bland to low grade dysplasia
  • Mitotic rate 1-5/50 hpf
• Some of the reported cases presented with a synchronous IPMN
• No reported association with invasive carcinoma
  • Intraductal tubular carcinoma does not appear to be related to intraductal tubular adenoma

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting : August 25, 2009

Supplemental studies

Immunohistology

KRAS mutations have been described

Differential Diagnosis

• Intraductal tubular carcinoma
• Intraductal papillary mucinous neoplasm (IPMN)
• Pancreatic intraepithelial neoplasm (PanIN)
• Mucinous cystic neoplasm (MCN)

Intraductal Tubular Adenoma	Intraductal Tubular Carcinoma
Composed of mucin positive pyloric type cells	Generally mucin poor or negative
Frequent goblet cells	No goblet cells
Low grade atypia	High grade atypia
Mitotic rate 1-5/50 hpf	Mitotic rate frequently >5/50 hpf
No necrosis	Frequent necrosis
Not associated with invasive carcinoma	May have associated invasive carcinoma

Intraductal tubular adenoma and carcinoma do not appear to be related

Intraductal Tubular Adenoma	Intraductal Papillary Mucinous Neoplasm
Discrete lesion	Usually diffuse lesion
Cystic dilation of ducts at tumor site with scant mucin	Distended ducts filled with mucin
Tubular pattern	Papillary pattern
Low grade atypia	Atypia may vary from low to high
MUC2 negative	MUC2 positive

Intraductal Tubular Adenoma	PanIN
Usually clinically detectable	Usually not clinically detectable
Grossly visible	Not grossly visible
Well formed tubules	No well formed tubules
Low grade atypia	Atypia may vary from low to high

Intraductal Tubular Adenoma	Mucinous Cystic Neoplasm of the Pancreas
Nodular intraductal growth	Mucin filled cyst or cysts
Low grade atypia	Atypia may vary from low to high
Males and females affected	Nearly all female
Involves segments of ducts	Does not communicate with ducts
Extensive tubule formation	No tubules
No ovarian type stroma	Ovarian type stroma

Lists

Cystic Pancreatic Lesions

• Acinar cell cystadenocarcinoma
• Acinar cell cystadenoma
• Enterogenous duplication cyst
• Epidermoid cyst in intrapancreatic accessory spleen
• Intraductal oncocytic papillary neoplasm
• Intraductal papillary mucinous neoplasm
• Islet cell / well differentiated neuroendocrine tumor (occasionally cystic)
• Lymphangioma
• Lymphoepithelial cyst
• Mucinous cystic neoplasm
• Paraduodenal wall cyst
• Pseudocyst
• Serous cystadenocarcinoma
• Serous oligocystic adenoma
• Serous microcystic adenoma
• Solid and cystic hamartoma
• Solid pseudopapillary neoplasm
• Squamoid cyst of pancreatic ducts
• von Hippel Lindau associated cystic lesions

Mucinous Pancreatic Lesions

• Colloid carcinoma
• Intraductal papillary mucinous neoplasm
• Mucinous cystic neoplasm
• Pancreatic intraepithelial neoplasia

Bibliography

• Katabi N, Klimstra DS. Intraductal papillary mucinous neoplasms of the pancreas: clinical and pathological features and diagnostic approach. J Clin Pathol. 2008 Dec;61(12):1303-13.

• Albores-Saavedra J, Sheahan K, O'Riain C, Shukla D. Intraductal tubular adenoma, pyloric type, of the pancreas: additional observations on a new type of  pancreatic neoplasm. Am J Surg Pathol. 2004 Feb;28(2):233-8.

• Nakayama Y, Inoue H, Hamada Y, Takeshita M, Iwasaki H, Maeshiro K, Iwanaga S, Tani H, Ryu S, Yasunami Y, Ikeda S. Intraductal tubular adenoma of the pancreas, pyloric gland type: a clinicopathologic and immunohistochemical study of 6 cases. Am J Surg Pathol. 2005 May;29(5):607-16.