Fibroma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
Overview
On gross pathology, solid white mass which is usually well-circumscribed is characteristic findings of ovarian fibroma. On microscopic histopathological analysis, ovarian fibroma is composed of spindle cells forming variable amounts of collagen. Sectioning of a fibroma typically reveals a chalky-white surface that has a whorled appearance, similar to that of a uterine fibroid. Areas of edema, occasionally with cyst formation, are also relatively common. On gross pathology, polypoid lesion which is usually small, is characteristic findings of oral fibroma. On microscopic histopathological analysis, fibrous stroma, collagen bundles, prominent vessels, and overlying squamous mucosa with hyperkeratosis and focal ulceration are characteristic findings of oral fibroma. On gross pathology, well circumscribed, metaphyseal lesion, and fragments of white-grey rubbery tissue are characteristic findings of chondromyxoid fibroma. On microscopic histopathological analysis, spindle cells or stellate cells in a myxoid or chondroid stroma, lobules with hypocellular centers and hypercellular peripheries, giant cells in a hypercellular periphery, and scattered calcifications are characteristic findings of chondromyxoid fibroma.
Pathophysiology
Ovarian Fibroma
Gross Pathology
On gross pathology, solid white mass which is usually well-circumscribed is characteristic findings of ovarian fibroma.
Microscopic Pathology
On microscopic histopathological analysis, fibroma is composed of spindle cells forming variable amounts of collagen. Sectioning of a fibroma typically reveals a chalky-white surface that has a whorled appearance, similar to that of a uterine fibroid. Areas of edema, occasionally with cyst formation, are also relatively common.
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Histopathology specimen of an ovarian fibroma high magnification
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Histopathology specimen of an ovarian fibroma intermediate magnification
Oral Fibroma
Gross Pathology
On gross pathology, polypoid lesion which is usually small, is characteristic findings of oral fibroma.
Microscopic Pathology
Following features are noted on microscopic histopathological analysis of oral fibroma:
- Fibrous stroma is a key feature
- Collagen bundles may be present
- Vessels may be prominent
- Overlying squamous mucosa is benign
- Hyperkeratosis may be present
- Focal ulceration may be present
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Histopathology specimen of a oral fibroma low magnification
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Histopathology specimen of a oral fibroma very low magnification
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Histopathology specimen of a oral fibroma intermediate magnification
Chondromyxoid Fibroma
Gross Pathology
On gross pathology, well circumscribed, metaphyseal lesion, and fragments of white-grey rubbery tissue are characteristic findings of chondromyxoid fibroma.
Microscopic Pathology
Following features are noted on microscopic histopathological analysis of chondromyxoid fibroma:
- Spindle cells or stellate cells in a myxoid or chondroid stroma
- Lobules with hypocellular centers and hypercellular peripheries
- Giant cells in the hypercellular periphery
- Scattered calcifications.
- No true hyaline cartilage formation is seen
- No mitotic activity is seen
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Histopathology specimen of a chondromyxoid fibroma showing stellate cells in myxoid stroma
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Histopathology specimen of a chondromyxoid fibroma showing lobule with calcification
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Histopathology specimen of a chondromyxoid fibroma showing stellate cells in myxohyaline stroma
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Histopathology specimen of a chondromyxoid fibroma showing stellate cells in myxoid stroma
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Histopathology specimen of a chondromyxoid fibroma showing focus of amorphous calcification
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Histopathology specimen of a chondromyxoid fibroma showing foci of amorphous calcification
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Histopathology specimen of a chondromyxoid fibroma showing stellate cells in myxohyaline stroma
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Histopathology specimen of a chondromyxoid fibroma showing Lobule with a darker (hypercellular) periphery and lighter (hypocellular) center. (SKB)
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Ossifying Fibroma (Osteofibrous dysplasia)
Gross Pathology
On gross pathology, discrete mass that is well delineated from surrounding bone, tan-white, rubbery cut surface, firm to gritty and no encapsulation are characteristic findings of ossifying fibroma.
Microscopic Pathology
Following features are noted on microscopic histopathological analysis of ossifying fibroma:
- They comprise of haphazardly distributed lamellated bony spicules on a background of fibrous stroma.
- Despite being benign, they can be locally aggressive.
- Immunohistochemical staining of lesions shows positive keratin cells in the majority of the cases.
- The lesion has a zonal architecture with a center of immature bone surrounded by more mature lamellar bone.
- The central spicules of woven bony trabeculae are lined by a layer of osteoblasts. The background is a loose and storiform fibrous tissue.
Pathogenesis
- Ossifying fibroma may be either a clonal neoplastic lesion or a developmental dysplasia.
Associated Conditions
- It be related to adamantinoma
Non-ossifying Fibroma (nonossifying fibroma, fibrous cortical defect, fibrous metaphyseal defect, fibroxanthoma of bone)
Gross Pathology
On gross pathology, fleshy, fibrous, yellow or tan-brown lesion with variable areas of haemorrhage are characteristic findings of non-ossifying fibroma.
Microscopic Pathology
The following features are seen on microscopic histopathological analysis of non-ossifying fibroma:
- Spindle cells without cytologic atypia are arranged in a storiform pattern.
- Scattered chronic inflammatory cells and benign giant cells.
- Foam cells and hemosiderin deposition are present.
- Mitoses are seen but cytologic atypia is absent.
Location
- Metaphysis of distal femur or proximal tibia (80%)
- Cortical
- Metaphysis
- Long bone
- Eccentric location
Associated Conditions
- Neurofibromatosis-type 1 (NF1)
- Fibrous dysplasia
- Jaffe-Campanacci syndrome
Desmoplastic Fibroma
Microscopic Pathology
The following features are seen on microscopic histopathological analysis of desmoplastic fibroma:
- Lamellar bone
- Fibrotic marrow space has following features:
- Collagen
- Low cellularity
- Spindle cells without significant atypia
- On histopathology, desmoplastic fibromas are identical to soft tissue desmoid tumors, with abundant collagenous stroma and little cellularity or pleomorphism.
- The main cell types that are seen include the following:
- Fibroblasts
- Myofibroblasts
- Undifferentiated mesenchymal cells
Pleural Fibroma
Microscopic Pathology
The following features are seen on microscopic histopathological analysis of pleural fibroma:
- Pleural fibromas are composed of irregularly arranged fascicles comprising of spindle cells with collagen separation.
- They originate from submesothelial mesenchymal cells.
- Myxoid or cystic degeneration can occur.
Location
- Approximately 80% of pleural fibromas arise from the visceral pleura, with the remainder arising from the parietal pleura. There may be a predilection towards the mid to lower zones of the chest.