Pathological Humeral Fracture from Bone Metastasis of a Gastrointestinal Stromal Tumour: First Reported Case

Background: Gastrointestinal stromal tumour (GIST) is the most prevalent mesenchymal tumour of the GI tract. Metastases commonly occur in the liver and peritoneum, with very rare reported cases of bone metastases, hence no therapeutic standard has been established for the management of bone metastases. Modern targeted therapy has improved patient survival, and although there are only a small number of reported GIST bone metastases, the incidence will likely continue to increase. Further understanding of GIST bone metastases is required for implementation of an accurate and effective treatment plan. Case presentation: We report a 56-years-old patient who has a history of bleeding duodenal GIST resected with a Whipple operation. Post-operatively, Imatinib was started, but she developed liver metastasis 6 years later, requiring segmentectomy. She reported pain over the left humerus 2.5 years later and sustained a trivial injury to the left arm, resulting in a distal humerus shaft spiral fracture associated with a radial nerve palsy (Holstein-Lewis injury). Images showed a lytic lesion with cortical erosion and soft tissue extension at the fracture site. Biopsy confirmed GIST bone metastases. She underwent an open reduction and internal fixation with plating and curettage of the lytic lesion, and made a good functional recovery afterwards. Conclusion: This is the first reported case of a GIST bone metastases pathological Holstein Lewis fracture. It highlights the potential for bone metastasis to present a long time after the diagnosis of a GIST. Although bone metastases are rare, it is now increasing due to the prolonged survival of patients and the introduction of targeted therapy. It is important to conduct long term surveillance in specific patient demographics and future studies should be carried out to facilitate the development of a surveillance protocol in patients with GIST.