Small Bowel Gastrointestinal Stromal Tumor as a Gateway for Streptococcus anginosus Causing Multiple Liver Abscesses

Abstract

Gastrointestinal stromal tumors (GISTs) are the most common type of mesenchymal neoplasm of the gastrointestinal tract but consist of only 1% of all primary gastrointestinal neoplasms. Differentiated from other spindle cell tumors, GISTs are uniquely positive for CD117 expression which allows for molecular targeting therapy with imatinib mesylate (Gleevec). Clinical presentations are variable, ranging from asymptomatic to vague symptoms of abdominal pain, early satiety, abdominal distention or gastrointestinal bleeding. Very rarely, patients can present with tumor-bowel fistula and intra-abdominal abscesses. In this article, we discuss a rare presentation of a middle-aged male with multiple liver abscesses found to have a primary small bowel GIST. This patient received prompt intravenous antibiotics; however, hepatic abscesses can be easily misinterpreted as cystic hepatic metastases which can delay appropriate therapy. Streptococcus anginosus was found to be responsible for the formation of the liver abscesses visualized on computed tomography (CT) scan. Similar to Streptococcus bovis, knowledge in the literature is arising about the association between S. anginosus and gastrointestinal malignancies. This case highlights the importance of identifying concomitant primary GISTs with intra-hepatic abscesses, as these lesions can be easily misconstrued as liver metastases and consequently mismanaged. We herein emphasize that hepatic abscesses are a potential sequela of GISTs and should thus prompt further investigation for potential malignancies, if warranted, so that there is no delay in treatment of these gastrointestinal tumors.

Keywords: Gastrointestinal stromal tumors; Gleevec; Imatinib mesylate; Liver abscess; Small bowel; Streptococcus anginosus.

Figure 1

Liver lesion (arrow) identified on axial CT scan of the abdomen and pelvis. CT: computed tomography.

Figure 2

Small bowel mesenteric mass (arrow) identified on CT scan of the abdomen and pelvis (axial and coronal views, respectively). CT: computed tomography.

Figure 3

Small bowel mass at the mesenteric root, status post biopsy.

Figure 4

Biopsy of small bowel GIST shows proliferation of bland appearing spindle cells with eosinophilic fibrillar cytoplasm arranging in short fascicular pattern, with minimal pleomorphism and low mitotic index (< 5/50 HPF) (a, × 10 objective magnification). The spindle cells are immuno-positive for CD117 (c-KIT) (b). GIST: gastrointestinal stromal tumor.