A case of small exophytic GIST of the jejunum

Clinical History

A 68-year-old woman came to our department with recurrent cramping pain in the epi-mesogastric region; ultrasound examination showed the presence of a solid lesion within the peritoneal cavity.

Imaging Findings

US detected a hypoechoic solid lesion (4 cm) anteriorly of the aorta with evidence of internal vascularisation at colour Doppler. Because of suspected lymphadenopathy, the patient underwent CT.
CT confirmed the presence of a solid mass with homogeneous density and strong arterial vascularisation after contrast medium injection, while in the venous phase homogeneous impregnation was noted. The exophytic mass was closely adherent to a jejunal loop, without creating dilatation of the stomach or jejunal loops. The small bowel barium enema did not show changes in the wall or lumen of jejunal loops.
MRI confirmed the presence of the mass based in the wall of a jejunal loop: the mass was hypointense on T1-weighted images and strongly hyperintense on T2-weighted images. Gastrointestinal stromal tumour (GIST) was suspected and the patient underwent surgery. Histologic diagnosis was cancer compatible with GIST, located in the submucosa, muscularis propria and subserosa of the jejunal wall.

Discussion

Gastrointestinal stromal tumours (GIST) are mesenchymal neoplasms that arise from the muscular wall of hollow viscera, particularly from the cells of Cajal, the pacemaker system of intestinal motility. They are rare with an incidence of 0.5-2/1000000 adults/year and represent 0.1-3% of all gastro-intestinal cancers. They may affect the entire digestive tract from the oesophagus to the rectum, but most frequently occur in the stomach (70 %) or in the small intestine (30 %), where they are at increased risk of malignant behaviour. The intestinal locations are often multiple. Important advances have been achieved in the diagnosis and treatment of GIST. The identification of KIT proto-oncogene, whose activation stimulates the proliferation of cancer cells, has allowed the development of a drug therapy based on a drug that inhibits the KIT receptor protein (Imatinib). Gastric GISTs can be detected by endoscopy and endoscopic ultrasound, while small bowel localisations are difficult to identify. CT and MRI play an important role for diagnosis tumor characterization. Findings that may suggest malignancy are diameter >5 cm, central necrosis, inhomogeneous density before and after contrast-enhancement, ill-defined margins, predominantly exophytic growth, invasion of surrounding structures. These findings are not always present in small lesions. CT and MRI are also essential for detecting liver, lung or peritoneal metastases, which are sometimes synchronous with the primary lesion. GISTs rarely involve lymphnodes. The treatment of choice is complete surgical resection or tyrosine-kinase-inhibitor chemotherapy (Imatinib).
The diagnosis is based on histology with the definition of KIT protein (CD 117) and mitotic index, although small lesions with low mitotic index may metastasise.

Differential Diagnosis List

Final Diagnosis

Gastrointestinal stromal tumour (GIST) of jejunum

URL:	https://www.eurorad.org/case/9091
DOI:	10.1594/EURORAD/CASE.9091
ISSN:	1563-4086