title: Morphologic Spectrum of Desmoid-Type Fibromatosis.
abstract: OBJECTIVE
  Desmoid-type fibromatosis is a locally aggressive neoplasm composed of long sweeping fascicles of bland fibroblasts/myofibroblasts. Tumors with classic features are easy to identify, but the morphologic spectrum of this entity spans beyond the conventional histologic pattern. Since sampling of an unrecognized histologic variant may lead to misdiagnosis, especially on small needle biopsy specimens, we sought to fully characterize the morphologic spectrum of this entity.
  
  
  METHODS
  We examined 165 cases of desmoid-type fibromatosis and catalogued the morphologic patterns and percentage of those patterns identified in each case. Clinicopathologic variables, including age, sex, location, and recurrence, were analyzed and correlated with pattern frequency.
  
  
  RESULTS
  Seven morphologic patterns were identified, including conventional, hyalinized/hypocellular, staghorn vessel, myxoid, keloidal, nodular fasciitis-like, and hypercellular. The mean number of patterns per case was two, but some cases harbored up to five patterns. The greatest morphologic variability was seen in the intra-abdominal lesions, with these tumors having a significantly higher percentage of the keloidal and staghorn patterns compared with extra-abdominal and abdominal wall sites. No significant correlation between patient outcome (recurrence) and presence of variant morphologic pattern was observed (P = .549).
  
  
  CONCLUSIONS
  The morphologic spectrum of desmoid-type fibromatosis is deceptively broad, and awareness of the variety of histologic patterns is critical for accurate diagnosis.
authors.affiliation: From the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN.
authors.forename: Riyam T
authors.initials: RT
authors.lastname: Zreik
authors.affiliation: From the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN. fritchie.karen@mayo.edu.
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Fritchie
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004502:Education, Medical, Continuing; D005260:Female; D005347:Fibroblasts / Q000473:pathology; D018221:Fibromatosis, Abdominal / Q000145:classification / Q000473:pathology*; D018222:Desmoid Tumors / Q000145:classification / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D058628:Myofibroblasts / Q000473:pathology; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000145:classification / Q000175:diagnosis / Q000473:pathology; D012189:Retrospective Studies; D012983:Soft Tissue Neoplasms / Q000145:classification / Q000473:pathology*; D055815:Young Adult
keywords: Aggressive fibromatosis; Deep fibromatosis; Desmoid tumor; Desmoid-type fibromatosis; Morphology