Mucinous breast carcinoma
|Mucinous breast carcinoma|
|Diagnosis in short|
Mucinous breast carcinoma. H&E stain.
|LM||malignant mucin producing glands - where mucinous component must comprise >90% of the tumour, tumour cells should float in the mucin, glands typically have irregular edges, +/-vessels within the mucin pools|
|LM DDx||other type of breast cancer with a mucinous component (very common), other mucinous tumours|
|IHC||ER +ve, PR +ve, HER2 -ve|
|Gross||pale, glistening, jelly-like appearance|
|Grossing notes||breast grossing|
|Staging||breast cancer staging|
|Site||breast - see invasive breast cancer|
|Prognosis||good compared to the usual ductal carcinoma|
|Clin. DDx||other breast tumours|
Mucinous breast carcinoma is an uncommon form of breast cancer that has a good prognosis compared to the common invasive ductal carcinoma.
It is also known as mucinous carcinoma of the breast, and colloid carcinoma of the breast.
- 2% of invasive breast carcinomas.
- Good prognosis.
- Usually older women.
- Pale, glistening, jelly-like appearance.
- Malignant mucin producing glands.
- Mucinous component must comprise >90% of the tumour - required for diagnosis.
- Small clusters of cells should float in the mucin - key feature.
- Glands typically have irregular edges.
- +/-Vessels within the mucin pools.
- Subtypes 
- Mucinous A (or paucicellular) - more mucin
- Mucinous B (or hypercellular) - less mucin and neuroendocrine differentiation and argyrophilia
- DCIS with a mucinous component.
- Mucin has a homogenous appearance, mucin lacks vascularization, mucin pools have a regular border.
- Invasive ductal carcinoma of the breast with a mucinous component - more common than mucinous breast carcinoma. Any 'no special type' component imparts a worse prognosis so the diagnosis 'mucinous carcinoma' is reserved for tumours with close to pure mucinous features.
- The amount of mucinous component to call mucinous carcinoma varies by anatomical site.
- A breast core biopsy that show any degree of mucinous change is an indication for excision to exclude mucinous carcinoma.
- Size and margins are assessed from edge of mucin, even if it does not contain epithelial cells
- These tumors can be very difficult to assess lymphovascular invasion. Look for tumour cells in areas where lymphatics are expected ie. tumour in arc-shape around vascular bundle
- ER +ve.
- PR +ve.
- HER2 -ve.
- Barkley, CR.; Ligibel, JA.; Wong, JS.; Lipsitz, S.; Smith, BL.; Golshan, M. (Oct 2008). "Mucinous breast carcinoma: a large contemporary series.". Am J Surg 196 (4): 549-51. doi:10.1016/j.amjsurg.2008.06.013. PMID 18809061.
- Dogan, E.; Aksoy, S.; Dizdar, O.; Arslan, C.; Dede, DS.; Ozisik, Y.; Altundag, K.. "Pure mucinous carcinoma of the breast: a single center experience.". J BUON 16 (3): 565-7. PMID 22006768.
- Weigelt, B.; Geyer, FC.; Horlings, HM.; Kreike, B.; Halfwerk, H.; Reis-Filho, JS. (Nov 2009). "Mucinous and neuroendocrine breast carcinomas are transcriptionally distinct from invasive ductal carcinomas of no special type.". Mod Pathol 22 (11): 1401-14. doi:10.1038/modpathol.2009.112. PMID 19633645.
- Jacobs, TW.; Connolly, JL.; Schnitt, SJ. (Sep 2002). "Nonmalignant lesions in breast core needle biopsies: to excise or not to excise?". Am J Surg Pathol 26 (9): 1095-110. PMID 12218567.