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 February 27th, 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
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
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
Contributed by Dr. Mark R. Wick
Images hosted on other servers:
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
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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.
Reference: Breast nonmalignant - Fibromatosis
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