Teaching Case

The patient, a woman with breast cancer, underwent an abdominal ultrasonography in order to stage the cancer. US showed an epigastric lesion. A CT examination and a biopsy were performed in order to define the lesion.

The patient, a 78-year-old female with recent diagnosis of breast cancer, underwent an abdominal ultrasonography to stage the cancer. US showed an epigastric nodular lesion, partially anechoic, having a peripheral vascularity. A CT examination was necessary in order to define the lesion. After the administration of intravenous contrast, CT showed a solid lesion originating from the wall of the lesser gastric curvature and with peripheral enhancement. This lesion had an area growing into the perigastric fat tissue and an area displacing gastric mucosa. There was no local infiltration.
These features were compatible with gastointestinal stromal tumour (GIST).
An endoscopic ultrasonography was performed and a biopsy was made: it confirmed the diagnosis of GIST.

Gastrointestinal stromal tumours are the most common mesenchymal tumours of the gastrointestinal tract. Stromal tumours represent less than 1% of all the gastrointestinal tract tumours. The prevalence of stromal tumours amounts to 20-40 per million inhabitants per year and that of inoperable and metastatic GIST amounts to 20-30%. The prevalence of GIST is similar in men and women. GIST usually appear in patients above 50 years of age and the maximum incidence is observed in the fifth and the sixth decade of life. In about 10% of patients with stromal tumours other malignancies such as clear-cell renal carcinoma, cervical, breast and lung carcinoma are encountered. There are a few reports of familial GIST.
More than 80% of the primary tumours are localised in the gastrointestinal tract. In about 10% of cases, primary GIST are found in the retroperitoneal space or in the pelvis. The majority of GIST (40-70%) are in the stomach and about 20-50% are localised in the small intestine. GIST may have submucosal, intramural or subserous localisation; the clinical presentation depends on the localisation and on the size of the tumour. About 10-30% of GIST are completely asymptomatic, and discovered incidentally during an endoscopic or radiologic diagnostic work-up. If present, the clinical symptoms are non specific and include abdominal pain, early satiety, flatulence, anaemia of unknown origin, weight loss, vomiting. Stomach tumours may cause epigastric pain, anorexia, nausea, vomiting and weight loss. There are two kinds of GIST metastases, haematogenous and lymphogenous, and these are usually limited to the abdominal cavity. The majority of metastases are found in the liver and in the peritoneum.
The diagnostic evaluation of GIST is based on imaging techniques; endoscopic examination usually describes GIST as submucosal changes observed through the gastrointestinal lumen as protrusions. Computed tomography shows GIST as solid masses that display contrast enhancement after intravenous administration. Endoscopic ultrasonography (EUS) plays an important role in the diagnostic work-up of stromal tumours. It shows GIST as hypoechogenic masses originating from different layers of the gastrointestinal tract wall, usually from the muscularis propria and muscularis mucosa. On the basis of EUS it is not possible to differentiate between stromal tumours and leiomyosarcomas: the final diagnosis is established on the basis of the histological examination of a biopsy specimen.
About 20% of malignant GIST are diagnosed when the neoplastic process has already generalised; it refers especially to small lesions, which for a long time are asymptomatic and are discovered incidentally. The clinical malignancy of the tumours increases in the more distal segments of the gastrointestinal tract.
Surgical treatment is the only chance of cure for patients with primary, i.e. localised GIST. There is no surgical consensus about laparoscopic or open surgical treatment; the tumour must be totally resected without opening it to prevent subsequent peritoneal seeding. Lymphadenectomy is generally not indicated because metastases to the lymph nodes are rare.