Development of multiple myeloma in a patient with gastrointestinal stromal tumor treated with imatinib mesylate: a case report.

Gastrointestinal stromal tumors (GISTs) are rare tumors, which represent approximately 1% of the neoplasms of the gastrointestinal tract. These tumors rarely give extra-abdominal metastases. However, their clinical outcome is potentially adverse. In some rare cases, co-existance of GISTs with other malignancies has been reported. Here we present a case of a 74-year old male with GIST, which was managed by surgical resection. Fourteen months later, the patient presented with liver metastases and imatinib mesylated was administered. During treatment, the patient reported skeletal pain and plane X-rays revealed osteolytic bone lesions. Further investigation revealed the presence of multiple myeloma. To the best of our knowledge, this is the first report of the co-existence of multiple myeloma (MM) with GIST.