Breast - nonmalignant
Benign tumors / changes
Nodular mucinosis of breast

Author: Cansu Karakas, M.D. (see Authors page)

Revised: 11 September 2015, last major update September 2015

Copyright: (c) 2002-2015,, Inc.

PubMed Search: Nodular mucinosis [title] breast
Definition / General
  • Very rare stromal lesion of breast with few cases reported
  • Terminology
  • Also called nerve sheath myxoma of breast (Virchows Arch A Pathol Anat Histopathol 1989;416:163)
  • Epidemiology
  • Mostly young females who present with a non-encapsulated, ill-defined mass in nipple / areola region (J Cutan Pathol 2010;37:1178, Arch Pathol Lab Med 2005;129:e58), but see Case Reports below
  • 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
  • 21, 30 and 37 year old women (Arch Pathol Lab Med 2005;129:e58, Breast Cancer 2002;9:261, SAJ Case Rep 2015;2:101)
  • 46 year old man (Dermatopathology 2014;1:47)
  • 72 year old women (Am J Dermatopathol 2010;32:187, J Am Acad Derm 2011;64:AB38)
  • Nodular mucinosis of breast in a supernumerary nipple (J Cutan Pathol 2010;37:1178)
  • Nerve sheath myxoma of breast (Virchows Arch A Pathol Anat Histopathol 1989;416:163)
  • Nodular mucinosis of breast (Pathol Int 1998;48:542)
  • Treatment
  • Excision; does not recur
  • Gross Description
  • Usually well circumscribed but not encapsulated, glistening, grayish, pink cut surface
  • Often multiple nodules of various sizes
  • Micro 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)
  • Micro Images
    Missing Image

    Various images

    Missing Image Missing Image Missing Image

    Various images

    Cytology Description
  • Mucin with no evidence of malignancy or epithelial components
  • Positive Stains
  • Spindle cells: vimentin, smooth muscle actin
  • Mucin (acidic): Hale's colloidal iron, Alcian blue (pH 2.5)
  • Capillary vessels: CD34
  • Negative Stains
  • PAS (stains only neutral mucins), mucicarmine
  • 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)