Cystic and intraductal lesions

Mucinous cystic neoplasm

Editorial Board Member: Catherine E. Hagen, M.D.
Enoch Kuo, M.D.
Raul S. Gonzalez, M.D.

Last author update: 15 April 2021
Last staff update: 11 July 2023

Copyright: 2002-2023,, Inc.

PubMed Search: Mucinous cystic neoplasm pancreas

Enoch Kuo, M.D.
Raul S. Gonzalez, M.D.
Page views in 2022: 16,135
Page views in 2023 to date: 15,165
Cite this page: Kuo E, Gonzalez RS. Mucinous cystic neoplasm. website. Accessed September 30th, 2023.
Definition / general
  • Benign or potentially low grade malignant cystic epithelial neoplasm composed of cells which contain intracytoplasmic mucin (ICD-O: 8470/0 [Accessed 18 February 2021])
  • WHO classification:
    • MCN with low grade dysplasia (adenoma)
    • MCN with high grade dysplasia (carcinoma in situ)
    • MCN with invasive carcinoma
Essential features
  • Cystic neoplastic lesion that is a precursor to pancreatic adenocarcinoma
  • May harbor invasive carcinoma
  • Presence of associated ovarian type stroma
ICD coding
  • ICD-10: C25 - Malignant neoplasm of pancreas (if malignant)
  • ICD-10: D13.6 - Benign neoplasm of pancreas (if benign)
  • Distal pancreas (> 95%) (Ann Surg 2008;247:571)
  • Can also occur in the liver and gallbladder
  • Metastases usually restricted to abdominal cavity; metastases to ovary may simulate primary ovarian tumors
  • Ectopic ovarian stroma is thought to be seeded from primordial ovarian cells at early stages of embryonic development
  • Cysts are later formed by hormones and growth factors released by the ovarian stroma (Am J Surg Pathol 1999;23:410)
  • No known etiology
Clinical features
  • Cytology and lab analysis of pancreatic cyst fluid from endoscopic ultrasound guided FNA
  • Histology of pancreatic resection
  • Elevated carcinoembryonic antigen (CEA) and presence of KRAS mutation in cyst fluid supports a mucinous cyst (includes MCN and intraductal papillary mucinous neoplasm) (Ann Gastroenterol;26:122)
Radiology description
  • Thick walled, single, septated cyst in the body or tail of the pancreas (Gut Liver 2015;9:571)
  • May have nodules or calcifications
Prognostic factors
Case reports
Gross description
  • Large (mean 10 cm)
  • Typically unilocular megacysts that do not communicate with ductal system, though up to 15% communicate with main pancreatic duct (Gut Liver 2015;9:571)
  • Cyst wall is papillary, trabecular or thickened
  • Has mucoid / watery cyst contents
  • Must sample solid areas within the cyst
Gross images

Contributed by Diana Agostini-Vulaj, D.O. and AFIP images

MCN with no connection to main duct

Unilocular cyst

Conspicuous, irregular, solid protuberances

Multiloculated cystic lesion

36 year old
woman: large
cyst with
solid tumor

Images hosted on other servers:

39 year old man with multilocular cyst with thick mucin

Microscopic (histologic) description
  • Large cyst lined by intestinal, pseudopyloric or gastric foveolar type epithelium that often form papillae, surrounded by characteristic dense ovarian type stroma (Gut Liver 2015;9:571)
  • Epithelial lining has variable atypia (none, low grade, high grade); scattered neuroendocrine cells may be present
  • Invasive adenocarcinoma may or may not be present; must sample extensively to rule out an invasive component (Gut Liver 2015;9:571, Am J Surg Pathol 1999;23:1320)
  • Calcifications are common
  • May have mural nodules with features of giant cell tumor, malignant fibrous histiocytoma or anaplastic carcinoma
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D. and Matthew W. Rosenbaum, M.D.

Spindled ovarian type stroma

Focal minute papillation

Foveolar mucinous epithelium

Classic ovarian type stroma

MCN with invasion

Estrogen receptor

Cytology description
  • Cyst aspirates are usually acellular with thick, gelatinous mucus
  • Clusters of 3 dimensional atypical glandular cells with hyperchromasia predict at least moderate dysplasia (Arch Pathol Lab Med 2009;133:388)
Cytology images

Contributed by Matthew W. Rosenbaum, M.D.

Cytology of mucinous cystic neoplasm

Positive stains
Negative stains
Molecular / cytogenetics description
  • KRAS mutations noted in in situ or invasive areas, inactivating SMAD4 and TP53 mutations in more advanced MCNs (Gut Liver 2015;9:571)
  • Negative for GNAS mutations
Sample pathology report
  • Pancreas and duodenum, Whipple resection:
    • Mucinous cystic neoplasm with low grade intraepithelial neoplasia (8.3 cm) (see comment)
    • Negative for high grade intraepithelial neoplasia or malignancy.
    • Focal background chronic pancreatitis
    • Margins of resection unremarkable.
    • Seven benign lymph nodes.
    • Comment: The gross cystic lesion was entirely submitted for microscopic analysis.
  • Pancreas and duodenum, Whipple resection:
    • Focal adenocarcinoma arising from a mucinous cystic neoplasm (see synoptic report)
Differential diagnosis
Board review style question #1
Which of the following findings on fine needle aspiration of a pancreatic cyst are most consistent with a mucinous cystic neoplasm?

  1. Decreased CEA, decreased amylase, no KRAS mutation, no GNAS mutation
  2. Elevated CEA, elevated amylase, KRAS mutation, GNAS mutated
  3. Elevated CEA, highly elevated amylase, no KRAS mutation, no GNAS mutation
  4. Elevated CEA, variable amylase, KRAS mutation, no GNAS mutation
Board review style answer #1
D. Mucinous cystic neoplasms have elevated CEA, variable amylase, KRAS mutation and no GNAS mutation. If a GNAS mutation is present, then the findings will favor an IPMN (answer B). Decreased CEA and amylase with no KRAS or GNAS mutations favor a serous cystadenoma (answer A). An elevated CEA and amylase without KRAS or GNAS mutations will favor a pancreatic pseudocyst (answer C).

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Reference: Mucinous cystic neoplasm
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