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http://upload.orthobullets.com/topic/8062/images/desmoid tumor.jpg
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Introduction
  • A fibrogenic lesion that is the most locally invasive of all benign soft tissue tumors
  • Epidemiology
    • incidence
      • 900 cases a year in US
    • demographics
      • younger individuals (25-35 years of age)
      • female>male (3:1)
      • higher incidence in familial adenomatous polyposis (FAP) and Gardner syndrome 4-30%
    • location
      • most common shoulder (20%) > chest wall/back (17%) > thigh (13%)
      • >50% are extra-abdominal
      • may have multiple lesions in the same extremity
        •  subsequent mass usually appears more proximally in the same limb
      • appears in sites of previous surgery or scars
  • Genetics
    • patient's with familial adenomatous polyposis (FAP) have increased risk for development of desmoid tumors  
      • 15% of tumors have adenomatous polyposis coli (APC) gene mutation (gene controls beta catenin)
      • elevated levels of beta catenin in all tumors
    • trisomy in chromosome 8 or 20
  • Associated conditions
    • Dupuytren contractures
    • Ledderhose disease
    • familial adenomatous polyposis (FAP)
    • Gardner syndrome
  • Prognosis
    • high risk of recurrence
    • highly unpredictable lesions
    • occasional spontaneous regression
    • no risk of metastasis or malignant transformation, unless related to radiation
Symptoms
  • Presentation
    • usually an enlarging mass
    • nerve compression
      • numbness, tingling, motor weakness, stabbing pain
  • Physical exam
    • has a distinctive "rock hard" feel on palpation
      • because tumor is fixed to surrounding tissues
    • poorly circumscribed
    • may be painful and limit motion around joint
Imaging
  •  Radiographs
    • play minimal role in diagnosis
    • some tumors encroach on/erode bone or trigger periosteal reaction that extends into tumor as "frond like" spicules of bone
  • MRI
    • Indications
      • best means to diagnose
      • exclude multicentric lesions (in the same extremity)
    • findings
      • low signal intensity on T1-weighted images
      • low to medium intensity on T2-weighted images
      • Gadolinium enhances appearance
      • infiltrates muscle
      • 5-10cm in size
      • may erode bone locally
Studies
  • Gross specimen
    • gritty
    • white
    • poorly encapsulated
  • Histology
    • Classic characteristics are 
      • well differentiated fibroblasts 
      • uniform spindle cells with elongated nuclei and occasional mitoses
      • abundant collagen
      • tumor infiltrates adjacent tissues
  • Molecular Genetics/Immunohistochemisty
    • positive 
      • 100% positive for estrogen receptor-beta  
      • somatostatin
      • cathepsin D
      • Ki-67
      • c-Kit
    • negative
      • estrogen receptor-alpha
      • progesterone receptor
      • HER2
Treatment
  • Nonoperative
    • low dose-chemotherapy only / tamoxifen 
      • indications
        • inoperable lesions
        • tamoxifen favored for failed/poor candidates for standard chemotherapy 
          • works because most lesions occur in women and are more aggressive in women, especially premenopausal
          • tamoxifen works via an estrogen receptor blockage
  • Operative
    • wide surgical resection with radiotherapy
      • indications
        • symptomatic lesion
        • recurrent lesion
          • local recurrence is common (reduced recurrence with radiotherapy)
      • external beam radiation dose 50-60Gy
Complications
  • Recurrence
    • margin negative
      • 28% recurrence with surgery alone
      • 6% recurence with surgery + radiation
    • margin positive
      • 39% recurence with surgery alone
      • 25% recurrnce with surgery + radiation
IBank
  Location
Xray
Xray
CT
B. Scan
MRI
MRI
Histo(1)

Case A

tibia
 
 
(1) - histology does not always correspond to case 


 

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