Fibromatosis

 

 

Common Sites:

    • (GI sites):
      • pelvis
      • mesentery

 

Gross Features:

    • firm
    • coarse white trabeculations resembling a scar
    • gritty sensation on cutting

 

Histologic Features:

    • Superficial fibromatosis (Dupuytren contracture, Peyronie disease):
      • Nodular or poorly-defined broad fascicles of mature-appearing fibroblasts
      • Cells surrounded by abundant dense collagen
    • Deap-seated fibromatosis (Desmoid tumors):
      • Poorly defined with infiltrative margins
      • Plump fibroblasts arranged in broad sweeping fascicles / parallel arrays
        • “tissue-culture fibroblasts” - Open/pale chromatin with delicate nucleolus
        • basophilic cytoplasm
      • Abundant collagen between cells
        • May be hyalinized
      • Conspicuous thin-walled, elongated, compressed vessels
        • Others are muscularized, open arteries
      • Extravasated RBCs
      • Mitoses infrequent
      • Regenerating muscle cells trapped within the lesion may look like multinucleated giant cells
      • Lymphoid aggregates sometimes
      • Calcification or chondro-osseous metaplasia rarely

 

 

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Beta-catenin

(nuclear)

 

 

SMA

Sometimes

 

Desmin

Sometimes

 

CD34 (neg)

 

 

CD117

(depends on antibody)

(not membranous)

+/-

 

 

Molecular features:

    • superficial fibromatosis:
      • Trisomy 3
      • Trisomy 8
    • Deap-seated fibromatosis:
      • Mutations in APC or beta-catenin genes (in majority)

 

Other features:

    • May be associated with trauma
    • May be associated with pregnancy or Crohn’s
    • Occurs as part of Gardner’s syndrome, related to FAP
    • 10-15% of sporadic cases recur
    • 90% of Gardner’s syndrome cases recur
    • Doesn’t metastasize

 

References:

    • Robbins 2005
    • Gastrointestinal and Liver Pathology 2005