A 45 year old man presents to a physician with back pain and facial pain. Physical examination demonstrates coarse facial features and kyphosis. Laboratory examination is remarkable for elevated alkaline phosphatase. .X-ray studies demonstrate skull thickening with narrowing of foramina, and bowing of the femur and tibia. Bone biopsy reveals a mosaic pattern of bone spicules with prominent osteoid seams. Which of the following neoplasms occurs at an increased frequency in patients with this disorder?