Radiological features of metastatic gastrointestinal stromal tumors

Abstract

The imaging features of 42 histopathologically confirmed cases of Gastrointestinal Stromal Tumors (GIST) were analyzed, to observe the pattern of metastasis. At presentation 22 of 42 patients (52.3%) showed metastasis. During follow-up, three more cases developed metastasis, within one year of resection. Mesentery, omentum, and liver were the most frequent sites for metastasis. Other sites that were rarely reported to be involved were increasingly recognized to show metastasis due to longer survival. The metastasis often showed attenuation and enhancement characteristics, similar to primary GIST, and frequently showed necrosis, hemorrhage, and calcification.

Keywords: Gastrointestinal stromal tumor; gastrointestinal neoplasia; metastasis; sarcomas; smooth muscle mesenchymal tumor.

Figure 1

NECT of a small bowel GIST with liver metastasis in a 42-year-old male. (a) Axial scan shows two well-defined, hypodense, space-occupying lesions in the liver. There is central necrosis. A small hyperdense focus within it is suggestive of a bleed (open arrow). (b) The primary mass shows heterogeneous enhancement (thin white arrow); another heterogeneously enhancing SOL can be seen in segment VI of the liver (solid thick arrow).

Figure 2

Contrast Enhanced Computed Tomography (CECT) of abdomen shows Jejunal GIST in a 32-year-old female patient. (a) CECT shows a large hypodense mass with neovascularity at the periphery in right and left lobes of the liver (white arrow) and central necrosis (open arrow) suggestive of hepatic metastasis (b) Multiple heterogeneously enhancing, space-occupying lesions (SOL) in the pouch of Douglas indenting on the rectum (open arrows) (c) Subcutaneous deposits seen in anterior abdominal wall in a subcutaneous plane (narrow arrow) and multiple peritoneal and omental deposits (broad open arrow). The lesions enhance with contrast. (d) The primary jejunal GIST shows central necrosis, peripheral neovascularity, and enhancement (broad open arrow).

Figure 3

CECT of the abdomen in a 45-year-old female patient shows rectal GIST with metastasis, before and after treatment. (a) Scan before treatment shows multiple solid enhancing SOL of varying sizes scattered in both lobes of the liver (open arrows). (b) After treatment the lesions are more hypodense, similar to the cyst, which is characteristic of metastatic deposits (two solid arrows). (c) The thick white solid arrow indicates rectal GIST; the lesion appears as a solid enhancing exophytic growth from the rectum; the thinner arrow indicates deposit in the pouch of Douglas. (d) After treatment the rectal GIST disappears and no mass is visible at the primary site (arrow).

Figure 4

CE-axial CT scan of the abdomen and pelvis, in a 32-year-old female patient, shows extensive peritoneal metastasis from the GIST and subcutaneous deposits obscuring the origin. (a) Multiple, solid, enhancing deposits are noted on both sides of the pelvis, abutting the uterus and rectum (open arrow); the white solid arrow indicates subcutaneous deposits. (b) Multiple omental deposits (open arrows) show heterogeneous enhancement; their origin is obscure. (c) Two discrete deposits in the liver show solid (white solid narrow arrow) and cystic (open wide arrow) components on a contrast-enhanced scan.

Figure 5

CECT of abdomen shows extensive peritoneal dissemination in a 45-year-old male. (a) Scan shows the entire peritoneal cavity is filled with solid enhancing SOL (thick solid arrow), displacing and compressing the mesentery and bowel loops (open arrow). (b) Scan shows scalloping of the liver, caused by a peritoneal deposit (thin open arrow); Also shows omental caking (thin white arrow) that mimics pseudomyxoma peritonei.

Figure 6

CECT of the abdomen shows Gastric GIST with hemoperitoneum in a 70-year-old male patient. The solid thick arrows that point to the primary lesion show heterogeneous enhancement and the other thin arrows point to the high density fluid within the peritoneal cavity, indicating hemorrhage.

Figure 7

CECT of the abdomen and pelvis shows small bowel GIST with lymph node metastasis, in a 56-year-old male (open arrow). (a) Scan shows a large heterogeneously enhancing lymph node in right inguinal region. (b) Scan shows a large heterogeneously enhancing mass with areas of necrosis in the upper jejunum (open arrow), which is the primary GIST.

Figure 8

CECT of the chest (lung window), CT pelvis in bone window, CT pelvis in soft tissue window, CT upper abdomen in soft tissue window, and CT pelvis, in that order, show anorectal GIST with spread to the lung, bone, peritoneum, and liver, in a 60-year-old male patient. (a) Section through the chest in a lung window shows small multiple lung nodules represented by multiple arrows; most of these are sub-pleural. (b) The open arrow shows an expansile lesion in lower sacrum – the cortex is disrupted both on the inner and outer aspects suggestive of metastasis. (c) Scan shows a solid heterogeneously enhancing exophytic growth on the right lateral wall of the rectum obliterating the lumen, suggestive of primary mass (open arrow). (d) In the same patient, scan shows liver metastasis in the left lobe (thick open arrow); neovascularity is seen at the periphery (thin open arrow). (e) Soft tissue window for sacral metastasis shows enhancement of the soft tissue in the lytic area (arrow).

Figure 9

CECT of the abdomen and thorax in a 61-year-old male shows gastric GIST presenting with hepatic and pulmonary metastases. (a) Non-enhanced CT shows hepatic metastasis and the primary mass (white arrow). Note that both the primary and secondary lesions are of similar density (thin arrow). (b) Scan shows multiple lung metastases (arrows). (c) Large solid enhancing SOL from the stomach lesion is predominantly exophytic.

Figure 10

Liver, peritoneal, and subcutaneous deposits in a 32-year-old female patient from a jejunal GIST; Follow-up scan revealed reduced vascularity and attenuation of the hepatic metastasis. (a) Pre-treatment liver metastasis scan shows intense vascularity (two arrows). (b) Scan shows subcutaneous deposits as a solid enhancing mass (small arrows); multiple peritoneal deposits (broad open arrow). (c) Scan post-treatment shows a marked reduction in vascularity and the lesion appears more cystic (thin open arrow).