Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Their most common metastatic sites are the liver and the peritoneum, but GISTs rarely metastasize to the bones. We report a case of a 58-year-old man with sternoclavicular joint metastasis from a GIST manifesting 28 months after surgical resection of the small intestine tumor. We will discuss through this paper and a literature review the clinical characteristics, imaging features, and management of this unusual metastatic location of GIST.
Gastrointestinal stromal tumors (GISTs) are the most common mesenchymatous tumors of the gastrointestinal tract [
Their most common metastatic sites are the liver and the peritoneum, but GISTs rarely metastasize to the bones. We will discuss through this paper and a literature review the clinical characteristic, imaging features, and management of this unusual metastatic location of GIST.
A 58-year-old man had undergone surgical removal of a small intestine tumor in January 2008. Histological examination showed a gastrointestinal stromal tumor with a 16 cm primary tumor in the jejunum. Immunohistochemistry revealed spindle cells positive for CD117 and CD34. Mitotic activity was low. No adjuvant treatment was available at that time. The patient was clinically stable and followed by serial imaging until May 2010, when he presented a painful sternoclavicular joint tumefaction. The thoracoabdominal CT scan revealed an osteolytic sternoclavicular joint mass (Figure
Bone metastasis in the sternoclavicular joint invading adjacent soft tissues.
Partial response after radiotherapy and 10 months of imatinib with partial reossification in the sternoclavicular joint and decreasing of the soft tissue extension.
Bone scintigraphy image showing increasing intensity of tracer uptake localized in the sternoclavicular joint.
Bone marrow biopsy: Spindle cells with high cellularity. Some of the tumor cells show mild pleomorphism. Numerous mitotic figures are present (
Positive immunostaining with c-Kit (CD117). Note diffuse membranous pattern (HE ×400).
After 19 months, the patient complained of weakness of lower limbs. Our patient refused vertebromedullary magnetic resonance imaging. A thoracoabdominal CT scan showed 2 metastatic osteolytic lesions of T1 and T10 vertebral body with spinal cord invasion. Urgent radiotherapy was directed at the T1 and T10 vertebra but stopped at the dose of 15 grays because of an affected general state. Our patient kept definitive paraplegia.
GISTs are defined as pleomorphic mesenchymal tumors of the gastrointestinal tract composed of spindle cells, epithelioid cells, or a combination of both that express the KIT protein (CD 117) and in most cases CD34 on immunohistochemistry [
GISTs have an uncertain clinical behavior ranging from benign to frankly malignant, making the outcome totally unpredictable. Over the years, many factors have been examined [
Bone metastases can be diagnosed rarely at disease presentation and more frequently at disease relapse [
Clinically, bone metastases are mostly symptomatic and revealed by bone fractures or bone pain as our patient or spin cord compression syndrome but they can be asymptomatic and are an incidental finding of the occasion of the practice of CT or PET-SCAN [
In our case, all bone lesions were osteolytic with invasion to the adjacent soft tissues. Di Scioscio described the radiologic aspect of bone metastases in a series of 3 cases. The lesions were mostly lytic, with a complete rearrangement of bone structure, cortex erosion, and, in one case, a solid mass invading adjacent soft tissues [
Few data can be found in the literature on the treatment of bone metastases in GISTs. The use of imatinib mesylate in recurrent or metastatic, resectable or not GIST in prospective trial has shown response in 50% patients, and in approximately 75–85% patients have at least stable disease. Imatinib mesylate has proven also efficacy in bone metastases of GIST [
GISTs are not considered as a radiosensitive tumor [
The effect of biphosphonate on GIST’s bone lesions is unknown, even though it may be recommended [
Bone metastases from GISTs are rare, and there are only a few reported cases in the literature, but they may become more prevalent due to increased patient life expectancy as well as the improvement in imaging techniques and they should always be sought. Imatinib is also an effective treatment in case of bone metastatic GISTs as was demonstrated in this case paper. Radiation therapy can be discussed in palliative indication.
The authors declare that there is no conflict of interests.