Desmoid tumors are benign neoplasms of the fibromatosis group. Desmoid tumors are fibrotic neoplasms of low metastatic potential. These tumors have long been associated with major laparotomy incisions.

Types and ocalization

 abdominal desmoid fibromatosis

• abdominal wall desmoid fibromatosis
  • thoracotomy and laparotomy incisions
  • laparoscopic trocar site
  • distal tubing of a cerebrospinal fluid shunt (#2944238#)

• intra-adfominal desmoid fibromatosis
  • mesenteric desmoid fibromatosis (mesenteric fibromatosis)

 extra-abdominal desmoid fibromatosis

• limb desmoid tumours
  • extremity desmoid tumours

Microscopical synopsis

 extensive microcalcifications and psammoma bodies (#3965088#)

Predisposition

 Gardner syndrome (APC gene mutations)

Associations

 muscular dystrophy associated with extra-abdominal desmoid tumor showing aberrant chromosome 1 [46,XX,add(1)(p36)] (#9508063#)
 melorheostosis (#8316873#)

Cytogenetics

 5q rearrangements (deletion 5q) (APC gene at 5q22) (#8976374#)

 trisomy 8 (correlated with tumor recurrence) (30%) (#9363449#, #8976373#, #8616800#)
 trisomy 20 (30%) (#8976373#, #8616800#, #7591262#)

CGH

 normal (56% to 83%) (#9739022#, #14499689#)

Losses

 5q22 (APC)
 6q16-q21 (14%) (#14499689#)
 5q14 (11%) (#9739022#)
 13q21-q31 (11%) (#9739022#)

Gains

 1q21 (39%) (#9739022#)
 9p12 (21%) (#9739022#)
 gain of chromosome 20 (32%) (#14499689#, #9739022#)
 No high-level amplifications detected (#9739022#)

Molecular biology

 monoclonality (#8816889#, #9060600#, #9098648#)
 somatic mutations in the APC gene (#8940264#, #11768389#)
 somatic mutations in the gene CTNNB1 coding for beta-catenin

Differential diagnosis

 fusiform cell tumors (spindle cell tumors)

• desmoid fibromatosis (deep fibromatosis)
• leiomyosarcoma
• myofibrosarcoma
• sclerosing epithelioid fibrosarcoma
• low-grade fibrosarcoma
• classic fibrosarcoma
• inflammatory myxohyaline/myxoinflammatory fibroblastic sarcoma
• nodular fasciitis
• synovial sarcoma
• inflammatory myofibroblastic tumor
• keloid
• other fibromatoses
  • infantile myofibromatosis
  • superficial fibromatoses (palmar fibromatosis, plantar fibromatosis, penile fibromatosis)

References

 Brandal P, Micci F, Bjerkehagen B, Eknaes M, Larramendy M, Lothe RA, Knuutila S, Heim S. Molecular cytogenetic characterization of desmoid tumors. Cancer Genet Cytogenet. 2003 Oct 1;146(1):1-7. PMID: #14499689#