Breast
Other benign tumors
Fibromatosis
Author: Monika Roychowdhury, M.D.
Topic Completed: 1 June 2017
Minor changes: 6 May 2021
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Fibromatosis [title] breast [title]
Table of Contents
Definition / general | Essential features | Terminology | Epidemiology | Sites | Clinical features | Radiology description | Radiology images | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Differential diagnosis | Board review style question #1 | Board review style answer #1Cite this page: Roychowdhury M. Fibromatosis . PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/breastfibromatosis.html. Accessed May 10th, 2021.
Definition / general
- Rare benign entity with clonal proliferation of fibroblasts and myofibroblasts similar to counterparts elsewhere
Essential features
- Rare benign entity characterized by spindle cell proliferation of fibroblasts and myofibroblasts as well as varying amounts of collagen
- No metastatic potential, however, it can have local recurrences
- Radiologically and grossly appears as a mass lesion
- Histology shows low grade myofibroblastic proliferation
- Treatment by wide local excision
Terminology
- Also referred to as desmoid tumor or low grade fibrosarcoma
Epidemiology
- Rare ( < 0.2% of primary breast tumors)
- Usually women of childbearing age, may be associated with trauma (Hum Pathol 2009;40:1564)
- Rarely reported in men (see Case reports below )
- Associated with Gardner syndrome, familial multicentric fibromatosis syndrome, silicone and saline breast implants and incidental and surgical trauma (Breast J 2006;12:66, AJR Am J Roentgenol 2005;185:488)
Sites
- May arise in mammary gland or in chest wall musculoaponeurotic tissue and extend into breast
Clinical features
- Firm, painless, mobile mass with or without skin / nipple retraction
- Infiltrative, locally recurrent if positive margins (25%) but nonmetastasizing (Am J Surg Pathol 1979;3:501, Am J Surg Pathol 1987;11:38)
Radiology description
- Irregularly shaped, high density with spiculated margin on mammography
- Ultrasound shows a poorly defined hypoechoic mass with posterior acoustic shadowing and an echogenic rim, closely mimicking cancer (AJR Am J Roentgenol 2005;185:488)
Radiology images
Contributed by Dr. Mark R. Wick
Mammogram
Images hosted on other servers:
Associated distortion and tenting of the underlying pectoralis muscle
Case reports
- 22 year old woman with desmoid tumor of the breast (J Plast Reconstr Aesthet Surg 2010;63:339)
- 30 year old woman with breast lump (Proc (Bayl Univ Med Cent) 2013;26:22)
- 39 year old woman with recurrent fibromatosis of the breast (World J Surg Oncol 2006;4:32)
- 39 year old woman with aggressive fibromatosis of the breast (Arch Pathol Lab Med 1985;109:260)
- 70 year old woman with fibromatosis (desmoid tumor) of the breast mimicking a case of ipsilateral metachronous breast cancer (World J Surg Oncol 2006;4:57)
- Fibromatosis of the breast (Breast J 2006;12:66)
Treatment
- Wide local excision with careful attention to negative margins although may recur even with negative margins (Ann Surg Oncol 2008;15:274)
Gross description
- Ill defined, white tan gray fibrous tissue
Gross images
Images hosted on other servers
Solid ill defined mass
Underlying chest wall
musculature, ribs and
parietal pleura
Microscopic (histologic) description
- Irregular, nonencapsulated proliferation of spindle cells forming interlacing fascicles with variable collagen deposition and cellularity
- Usually extends into surrounding fat and glandular parenchyma
- May have focal lymphoid aggregates at periphery
- May contain eosinophilic inclusions similar to those of infantile digital fibromatosis
- No / rare mitotic figures
- No epithelial component
Microscopic (histologic) images
AFIP images
Neoplastic infiltrate surrounds ducts and lobules
Sparsely cellular collagenous area with lymphocytes
Spindle cells with uniform nuclei and no mitotic activity
Keloidal collagen surrounds atrophic duct
Spindle cells in myxoid stroma
Focally, cells have large hyperchromatic nuclei
Contributed by Dr. Mark R. Wick
Various images
Images hosted on other servers:
Bland spindle cells and collagen
Mammary ductal epithelium
Myofibroblastic spindle cells
Low grade myofibroblastic proliferation
Invading muscle
Fig A: Infiltration into adjacent breast tissue
Fig B: Infiltration into skeletal muscle
Fig C: Monotonous, bland spindle cells with abundant
extracellular collagen, occasional small nucleoli
Cytology description
- Hypocellular spindle cells with no / rare glandular elements
Positive stains
- Vimentin, smooth muscle actin (focal)
Negative stains
Electron microscopy description
- Fibroblasts and myofibroblasts
Molecular / cytogenetics description
- Nuclear accumulation of beta-catenin in stromal tumor cells (82%), somatic alterations of APC / beta-catenin pathway (79%, Hum Pathol 2002;33:39)
Differential diagnosis
- Benign fibrous histiocytoma (superficial): storiform pattern of spindled and bland fibroblasts and histiocyte-like cells in middermis and subcutaneous tissue with infiltrative margins but sparing epidermis
- Benign stromal spindle cell tumors: circumscribed, no collagen, CD34+
- Inflammatory myofibroblastic tumor: prominent inflammatory infiltrate
- Metaplastic carcinoma - fibromatosis-like variant: epithelial component is atypical, keratin+
- Nodular fasciitis: superficial, well circumscribed, zonation effect with hypocellular central region and hypercellular periphery; feathery, tissue culture-like growth pattern due to abundant ground substance; often with mucoid pools (microcysts)
- Phyllodes tumor: stromal component
Board review style question #1
A 39 year old woman presents with a 3 cm left breast mass with skin retraction. Histological examination of the needle core biopsy shows a predominantly benign spindle cell proliferation intermixed with varying amounts of collagen. A rare focus shows benign glandular elements. SMA is positive; ER, PR is negative. What would be your recommendation for this patient?
- Benign lesion, no further treatment needed
- Phyllodes tumor, needs lumpectomy
- Tumor reduction by chemoradiation prior to surgery
- Wide local excision
Board review style answer #1
D. Wide local excision - fibromatosis should be treated by wide local excision to prevent local recurrences. No other therapy is needed unless the lesion is unresectable due to its extension into surrounding structures.
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Reference: Fibromatosis
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Reference: Fibromatosis
