An Unusual Pelvic Mass in a Pediatric Patient: A Case Report and Review of the Pathology.

Introduction: 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.

Case: 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.

Discussion: 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.

Conclusions: 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.