Squamoid Cyst of Pancreatic Ducts

Definition

• Pancreatic ductal cystic lesion lined by squamoid epithelium

Diagnostic Criteria

• Unilocular cystic dilation of duct
  • 0.8 - 9 cm
    • Smaller lesions may be noted incidentally
  • No papillae
  • No solid areas
• Lined by bland squamoid epithelium
  • Flattened squamous to transitional
  • Single layer to transitional
  • No keratinization or granular layer
  • No columnar or mucinous component
• Surrounded by thin band of fibrous tissue
  • No surrounding fibrosis or pancreatitis
• Lacks following features
  • Lymphoid tissue
  • Splenic tissue
  • Ovarian type stroma

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

Original posting : August 1, 2007
Update : April 26, 2009

Supplemental studies

Immunohistology

Differential Diagnosis

• Lymphoepithelial cyst
• Dermoid cyst
• Epidermoid cyst in intrapancreatic accessory spleen
• Serous oligocystic adenoma
• Incidental squamous metaplasia

Most other cysts are easily distinguished by their non-squamous lining

Lymphoepithelial Cyst of the Pancreas	Squamoid Cyst of Pancreatic Ducts
Surrounding dense lymphoid tissue	No surrounding lymphoid tissue
Overt keratinization	Non-keratinized
Usually peripancreatic	Intraductal

Squamoid Cyst of Pancreatic Ducts	Dermoid Cyst
No skin appendages or mesenchyme	Skin appendages and mesenchyme common
No overt keratinization	Keratinized

Epidermoid Cyst in Intrapancreatic Accessory Spleen	Squamoid Cyst of Pancreatic Ducts
Surrounded by splenic red pulp	Lacks surrounding splenic red pulp
May show overt keratinization	Non-keratinized
Involves tail of pancreas	Intraductal

Serous Macrocystic / Oligocystic Adenoma	Squamoid Cyst of Pancreatic Ducts
Lined by clear cells	Lined by squamoid cells
GLUT1 positive	GLUT1 at most focally positive

Incidental squamous metaplasia of pancreatic ducts lacks cyst formation

Clinical

• Rare, 1% of pancreas cystic lesions
• Age range 52-79
• M = F
• May be associated with elevated CEA or CA19-9
• Benign

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

Bibliography

• Othman M, Basturk O, Groisman G, Krasinskas A, Adsay NV. Squamoid cyst of pancreatic ducts: A distinct type of cystic lesion in the pancreas. Am J Surg Pathol. 2007 Feb;31(2):291-7.
• Basturk O, Coban I, Adsay NV. Pancreatic cysts: pathologic classification, differential diagnosis, and clinical implications. Arch Pathol Lab Med. 2009 Mar;133(3):423-38.