Pathology of Desmoid Fibromatosis

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Pathology of Desmoid Fibromatosis

• Alessandro Franchi, MD
• Dept. of Human Pathology and Oncology
• University of Florence, Italy

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Desmoid Fibromatosis

• Definition
• Clonal fibroblastic/myofibroblastic proliferation
  arising in the deep soft tissues characterized by
  infiltrative growth and tendency toward local
  recurrence but inability to metastasize

WHO 2002
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Desmoid Fibromatosis
Demographic features in 90 patients (1998-2002)
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Extraabdominal Fibromatosis

• Distribution in 61 cases
• Head Neck 5.0
• Shoulder 24.5
• Upper arm 6.5
• Forearm 6.5
• Chest wall 10.0
• Buttock, hip 16.0
• Thigh 24.0
• Lower leg 7.5

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Extraadbominal desmoid fibromatosis
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Adbominal desmoid fibromatosis
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Intraadbominal desmoid fibromatosis
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Desmoid Fibromatosis

• Genetics
• Trisomies of chromosomes 8 and/or 20 in 30
• Inactivation of APC tumor suppressor on
  chromosome arm 5q
• Activating mutations of ß-catenin

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Desmoid Fibromatosis

• Immunohistochemistry
• ß-catenin nuclear staining
• 80 sporadic
• 65-100 FAP associated
• Actins variable expression
• Desmin focal in rare cases
• CD34 negative
• C-kit negative

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Desmoid FibromatosisDifferential diagnosis
Extraabdominal

• Low grade spindle cell sarcomas
• Low grade (myo)fibrosarcoma
• Low grade fibromyxoid sarcoma

• Benign fibroblastic
• proliferations
• Hypertrophic scar/keloid
• Nodular fasciitis
• Desmoplastic fibroblastoma
• Gardners fibroma

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Desmoid FibromatosisDifferential diagnosis
Intraabdominal

• Gastrointestinal stromal tumor
• Sclerosing mesenteritis
• Ormonds disease (idiopathic retroperitoneal
  fibrosis)

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Low grade myofibrosarcoma
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Molecular Markers in Fibroblastic Tumors
  Desmoid LG-FS HG-FS Ki-67 0
32 86 p53 4 20 29 RB
0 56 93 Bcl-2 0
48 57 P lt 0.01
Hoos et al., Cancer Res 2001
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Low grade fibromyxoid sarcoma
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t(716) (q32-34p11)
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(Fibro)sarcomatous transformation of
fibromatosis does it occur?
Most cases interpreted as such are

• Fibromatoses with hypercellular areas
• Well-differentiated fibromatosis-like areas in
  fibrosarcomas

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Keloid/Hypertrophic scar
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Gardners fibroma

• Infants, children, adolescents
• Paraspinal regiongtbackgtchest wallgthead neck
  often multiple
• Proliferation of bland fibroblasts with thick
  collagen bundles (identical to nuchal-type
  fibroma)
• Superficial or deep soft tissues entrapment of
  surrounding structures (muscle, fat)
• Association with desmoid-type fibromatosis and
  FAP/Gardners syndrome

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CD34
CMA
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Gardners fibroma

• Immunohistochemistry
• CD34 in 80
• Nuclear reactivity for ß-catenin in 64
• Nuclear reactivity for both cyclin-D1 and C-myc
  in 100

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Gardners fibroma

• Correlation with Desmoid Fibromatosis
• Desmoid-type fibromatosis may develop at the site
  from which a Gardner fibroma has been initially
  excised (surgical trauma?)
• Features of desmoid-type fibromatosis and Gardner
  fibroma may coexist in the same lesion

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Desmoid Fibromatosis
Gardner Fibroma
Wehrli BM et al. Am J Surg Pathol 2001
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Gardners fibroma

• Clinical Significance
• Sentinel event for the detection of Gardner
  syndrome in older family members
• Sentinel event for the detection of a spontaneous
  mutation in the proband
• Close association with desmoid fibromatosis

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Thanks for your attention!