Other carcinoma subtypes, WHO classified

Topic Completed: 1 August 2012

Minor changes: 21 June 2020

Copyright: 2002-2019,, Inc.

PubMed search: Mucinous carcinoma [title] breast

Monika Roychowdhury, M.D.
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Cite this page: Roychowdhury M. Mucinous. website. Accessed November 25th, 2020.
Definition / general
  • Clusters of small uniform cells floating in lakes of extracellular mucin
  • Mucin accumulation may be due to inversion of polarity in cell, with mucin secretion directed towards base of cell / stroma, rather than luminal border
  • Tumor cells also produce MUC2, a distinctive mucin type (Am J Surg Pathol 2003;27:571, Hum Pathol 1998;29:1517, Histopathology 2003;42:26)
  • Classified as type A (paucicellular / no neuroendocrine differentiation), type B (hypercellular / neuroendocrine differentiation) or type AB (intermediate form), although no clinical significance
  • Based on molecular studies, mucinous type A is distinct from mucinous type B, and mucinous type B is part of a spectrum with neuroendocrine carcinoma (Mod Pathol 2009;22:1401)
  • Pure if 90% of more mucinous / colloid component
  • Cases with 75% - 90% mucinous / colloid component are considered a mixed variant with a prognosis worse than pure mucinous carcinoma, and dependent on the grade of the remaining carcinoma component
  • Dictionary definition of colloid:
    • a. gelatinous material resulting from colloid degeneration in diseased tissue;
    • b. resembling product of thyroid gland;
    • c. system in which finely divided particles are dispersed within a continuous medium in a manner that prevents them from being filtered easily or settled rapidly
  • Also called gelatinous carcinoma
Clinical features
Prognostic factors
  • 10 year survival for pure form is > 90% (much better than ductal carcinoma NOS)
  • Death may occur late, although 20 year breast cancer specific survival is still > 80%
Case reports
Clinical images

Contributed by Mark R. Wick, M.D.


Gross description
  • Soft, pale, grayish blue, gelatin-like and well circumscribed
  • Frequently hemorrhagic
Gross images

Contributed by Mark R. Wick, M.D.


AFIP images

Images hosted on other servers:

Gelatinous or jelly-like cut surface

Ill defined margins

Tumor with positive margin (Fig 1A / 1B)

Soft, gelatinous mass

Microscopic (histologic) description
  • Well differentiated (low grade) tumor cells floating in a sea of lightly staining amorphous mucin
  • Tumor cells may be solid, acinar or detached
  • Often surrounded by connective tissue bands
  • Recommended that at least 1/3 of tumor volume should consist of mucin, and that no areas of typical invasion should be present (Pure Mucinous Carcinoma of the Breast - Stanford University)
  • No / rare mitotic figures
  • Usually no in situ epithelial component
  • Note: recommended to designate tumors as pure (at least 90% mucinous component) or mixed
Microscopic (histologic) images

Scroll to see all images:

Contributed by Andrey Bychkov, M.D., Ph.D.

Floating cells


Contributed by Mark R. Wick, M.D.


Mucicarmine stain


Case of the Week #11

AFIP images

Alveolar and festoon patterns surrounded

Sparse epithelial component (arrow - DCIS) by mucin

Clusters of tumor cells
in mucinous secretion
surround a duct

Clusters of tumor cells

Grimelius staining (an agryophilic silver stain) denotes neuroendocrine differentiation

Images hosted on other servers:

Nuclear atypia is mild

Abundant mucinous stroma containing epithelial tumor cells with at most mild atypia

Contributed by Dr. Semir Vranic, University of Sarajevo (Bosnia)

Tumor cells are ER+

H&E, CU-18



Cytology description
  • Highly cellular, loosely cohesive clusters and dissociated cells with intact cytoplasm and nuclei with mild atypia, no oval bare nuclei
  • Also thin walled capillaries, micropapillary pattern of angulated clusters or abortive papillae and ball-like clusters (Acta Cytol 2007;51:25), abundant extracellular mucin (Malays J Pathol 2000;22:65)
  • May have spindle cells at edge of nests and in background, which represent either tumor cells compressed by mucin or fibroblasts (Diagn Cytopathol 2009;37:393)
  • Variable psammoma bodies (Diagn Cytopathol 2007;35:230)
Cytology images

Contributed by Mark R. Wick, M.D.

Grimelius stain

Images hosted on other servers:


Various images

Colloid carcinoma

Positive stains
Electron microscopy description
Electron microscopy images

AFIP images

Cytoplasmic mucigen granules

Molecular / cytogenetics description
  • Usually diploid

Histopathology Breast - Colloid carcinoma
Differential diagnosis
  • Infiltrating ductal carcinoma with focal mucinous change
  • Invasive micropapillary carcinoma: less extracellular mucin than mucinous carcinoma; cells have abundant eosinophilic cytoplasm, round vesicular nuclei and prominent nucleoli; extensive true angiolymphatic invasion; often psammoma bodies
  • Metastatic mucinous carcinoma (rectum - Asian J Surg 2006;29:95)
  • Mucinous ductal carcinoma in situ: noninvasive, myoepithelial cells (calponin+, p63+) are present
  • Mucocele-like lesion: myoepithelial cells are present and adherent to strips of cells floating in mucin, also ducts extended by mucinous material
  • Myxoid fibroadenoma: has compressed spaces lined by 2 layers
  • Signet ring cell carcinoma: intracellular mucin only
  • FNA: infiltrating ductal carcinoma: marked atypia (Am J Clin Pathol 2003;120:194)
  • FNA: myxoid fibroadenoma: stromal fragments and oval bare nuclei in every case
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