Breast nonmalignant
Nonneoplastic changes
Nodular mucinosis of breast

Topic Completed: 1 September 2015

Minor changes: 28 August 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Nodular mucinosis breast

Cansu Karakas, M.D.
Page views in 2019: 1,013
Page views in 2020 to date: 370
Cite this page: Karakas C. Nodular mucinosis of breast. website. Accessed May 27th, 2020.
Definition / general
  • Very rare stromal lesion of breast with few cases reported
Clinical features
  • Slow growing, soft, nontender, lobulated mass in subareolar region
  • No recurrence or metastases have been reported
Radiology images
  • Well circumscribed, lobulated, homogenous mass by ultrasonography
  • Lobular, radiopaque mass with no microcalcifications or spicles by mammography (Arch Pathol Lab Med 2005;129:e58)
Case reports
  • Excision; does not recur
Gross description
  • Usually well circumscribed but not encapsulated, glistening, grayish, pink cut surface
  • Often multiple nodules of various sizes
Microscopic (histologic) description
  • Unencapsulated nodules of irregular pools of mucin in a loose fibrocollagenous stroma separated by vascularized fibrous septa
  • Scattered histiocytes and occasional mast cells
  • Spindle shaped fibroblasts with pale cytoplasm, indistinct borders, bland and elongated nuclei
  • No mammary ducts, no mitotic figures, no invasion, no epithelial components within the nodules (may be at periphery)
Microscopic (histologic) images

Images hosted on other servers:

Various images

Various images

Cytology description
  • Mucin with no evidence of malignancy or epithelial components
Positive stains
Negative stains
Differential diagnosis
  • Carney syndrome: presence of other clinical signs, such as hyperpigmentation, usually presents at birth, presence of family history (FEBS Lett 2003;546:59)
  • Cutaneous follicular mucinosis: two types - either mucin is present in hair follicles or associated with cutaneous T cell lymphoma
  • Mucocele-like lesions: due to rupture of ducts extending into breast stroma, PAS+ and mucicarmine+
    • May be accompanied by atypical ductal hyperplasia or intraductal carcinoma
  • Myxoid liposarcoma: vascular, plexiform capillary pattern, S100+ lipoblasts
  • Myxoid variant of MFH: storifom pattern and large, pleomorphic malignant histiocytes
  • Myxoid neurofibroma: S100+ spindle cells in a fibrillary background
  • Superficial myxoid fibroadenoma: near nipple in young woman but usually involves the mammary ducts; mixture of epithelial and myepithelial cells which are cytokeratin+ and calponin+ respectively (Am J Surg Pathol 1991;15:713)
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