title: An Unusual Pelvic Mass in a Pediatric Patient: A Case Report and Review of the Pathology.
abstract: Neurofibromatosis type 1 (NF1) is the most commonly inherited autosomal dominant disorder in humans. NF1 patients have increased risk for gastrointestinal stromal tumors (GISTs). A Meckel's diverticulum (MD) represents a persistent embryonic omphalomesenteric duct characterized as a true diverticulum located near the ileocecal valve. We report a unique clinical case whereby a patient with NF1 developed a GIST within a MD.
  
  
  
  An adolescent male with NF1 presented with persistent lower abdominal pain. Clinical evaluation demonstrated a large pelvic mass. In the operating room, the mass was noted to emerge from a MD. Final pathology demonstrated a GIST with negative margins and CD117 positivity.
  
  
  
  Patients with NF1 are at increased risk for mesenchymal tumors including malignant peripheral nerve sheath tumors. GISTs are the most important and frequent non-neurological malignancy in NF1 and develop in ∼7% of NF1 patients. GISTs tend to be multifocal in NF1; however, they rarely occur within a Meckel's diverticula.
  
  
  
  Our case represents a rare case of a patient with NF1 who developed a symptomatic GIST within a MD. We recommend utilizing laparoscopy to determine resectability and clarify the diagnosis in this unique patient population who are at risk for multiple neoplasms.
authors.affiliation: Departments of *Surgery and Pediatrics ‡Laboratory Medicine and Pathology, University of Minnesota †University of Minnesota Medical School, Minneapolis, MN.
authors.forename: Brent D
authors.initials: BD
authors.lastname: Bauman
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Moertel
authors.forename: Eugene
authors.initials: E
authors.lastname: Zheng
authors.forename: Amanda
authors.initials: A
authors.lastname: Louiselle
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Berdan
authors.forename: David
authors.initials: D
authors.lastname: Berger
authors.forename: Bradley
authors.initials: B
authors.lastname: Segura
mesh_terms: D000293:Adolescent; D003937:Diagnosis, Differential; D046152:Gastrointestinal Stromal Tumors / Q000473:pathology*; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008467:Meckel Diverticulum / Q000175:diagnosis*; D009456:Neurofibromatosis 1 / Q000150:complications* / Q000473:pathology