Unusual presentation of a pancreatic cyst resulting from osteosarcoma metastasis.

Pancreatic metastases are uncommon. They have been reported in lung cancer, gastrointestinal malignancies, breast cancer, renal cell carcinoma, melanoma, lymphoma and sarcoma, and usually have solid morphology. Cystic metastasis to the pancreas is even more rare with few case reports in the literature. However, with the increasing use of computed tomography and magnetic resonance imaging as well as endoscopic ultrasound, more such lesions may be detected. Metastasis to the pancreas from osteosarcoma is highly unusual, but can be seen with the increasing survival of patients with osteosarcoma. We present an extremely rare case of a predominantly cystic lesion of the pancreas, which was diagnosed as metastasis from osteosarcoma. The pathophysiology of the cystic component of the metastasis of osteosarcoma is unknown. Cystic necrotic degeneration of the solid metastasis or pancreatitis secondary to the metastasis with development of associated fluid collection can be considered. Metastasis should remain a differential consideration even for primarily cystic lesions of the pancreas.