A 63-year-old man presents with left upper quadrant pain. He had been discharged from the hospital the previous week with a diagnosis of hypertensive urgency.
He complains of progressive abdominal pain for three weeks with acute worsening today.
He denies trauma, urinary complaints, chest pain, cough, fever, diarrhea, and constipation.
This is what the CT scan demonstrates.
What is the diagnosis? See next page.
Diagnosis: Gastrointestinal Stromal Tumor
Gastrointestinal stromal tumor (GIST) is one of the most common mesenchymal tumors of the gastrointestinal tract, but represent only one percent of all gastrointestinal tumors. These non-epithelial cell connective tissue tumors (sarcoma) develop in the muscularis propria layer (deep to the luminal mucosa and submucosa) of the intestinal wall.
Most tumors develop in the stomach (70%) with others developing in the small intestine (20%), colon and rectum (5%), and esophagus (<5%). (Int J Colorectal Dis 2012;27:689.) Tumors develop from the autonomic abdominal pacemaker cells — the interstitial cells of Cajal (ICC) — with most being from sporadic mutation in the c-kit gene, a receptor for a stem cell growth factor. (Int J Surg Pathol 2002;10:81.) Familial mutation does occur, and in some cases is associated with skin hyperpigmentation changes. Of note, patients with neurofibromatosis type I (NF1) have a high incidence of GISTs.
Patients may have vague complaints of abdominal pain and fullness, early satiety, nausea, vomiting, weight loss, melena, or anemia. (Surgery 1996;119:171.) Patients with large tumors may present with signs of local abdominal organ ischemia, obstruction, and rarely visceral perforation. Patients are typically middle-aged and rarely under 40 years old.
Initial recognition of GIST tumors may be via CT scan or endoscopic ultrasound. (Z Gastroenterol 2012;50:457.) Ulceration of the superficial luminal tissue occurs in half of cases, which can be visualized on endoscopy or appear as bulls-eye lesions on barium swallow studies. Tumors can become large and grow in an exophytic fashion and develop central necrosis and evolve into hemorrhagic fluid-filled cavitations.
Biopsy is required to rule out a malignant lesion. The diagnosis is confirmed by histopathology and immunohistochemistry staining (c-kit stain). (Am J Surg Pathol 2001;25:979.)
Lesions are typically benign (up to 80%), but malignant transformation with local and distant metastasis can occur. Treatment is therefore indicated for all tumors, depends on the tumor size, location, and rate of growth (mitotic rate), and is still somewhat controversial. (Ann Surg 2000;231:51; Semin Diagn Pathol 2006;23:70.) Smaller lesions are usually treated with surgical excision.
Use of the c-kit tyrosine kinase inhibitor imatinib (Glivec/Gleevec) in the past five years has revolutionized GIST chemotherapeutic treatment, improving survival rates. (J Gastrointest Cancer 2012;43:547.) Prior to the past decade, surgical treatment alone produced a typical median survival rate of two years or less. (Ann Surg 2000;231:51; Hematol Oncol Clin North Am 2012;26:1239.) Today the survival rate is five years, with 20 percent of patients progression-free after 10 years of treatment. (Discov Med 2012;13:357.) The optimal treatment of GIST tumors is still debated. (Ann Oncol 2009;20[Suppl 4]:64.)
This patient was found to have a large abdominal tumor that extended from the gastric fundus to the pelvis, with compression on the left renal vasculature. The patient was started on adjuvant chemotherapy for debulking with a plan for operative intervention.