Quick Case Study

A Benign “Knot” That Transformed Into a Dangerous Malignancy

A 30-year-old white man first noticed a knot in his right bicep and shoulder pain in spring 2012. His primary care physician first believed it was not a serious problem. But, when the patient’s shoulder pain continued to grow, radiographic evidence indicated a tumor. He was referred to a surgeon to remove the “knot.”

However, the surgeon found more tumors in the cartilage between the patient’s shoulder and arm. The tumors grew back after removal, requiring 3 additional surgeries. He was then referred to the Duke Cancer Institute.

Question: What is this patient’s likely diagnosis, and what treatment options are available to him?

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Answer: The patient was initially diagnosed with synovial chondromatosis, a rare condition of benign lumps of cartilage in the joints, that eventually progressed to chondrosarcoma. Chondrosarcoma rarely responds to chemotherapy or radiotherapy, so surgery is typically the only option.

Results on biopsy confirmed that the tumors were malignant. Once the patient arrived at Duke, magnetic resonance imaging (MRI) revealed that the cancer had metastasized. Will Eward, MD, DVM, an orthopaedic oncology surgeon at Duke Medicine, removed part of the patient’s neck, all of his arm (including the shoulder blade, the clavicle, and associated muscles), and many of the muscles in his back. Thoracic surgeon Thomas D’Amico, MD, removed 3 nodules from the patient’s lungs.

Synovial chondromatosis can be idiopathic or it can result from an underlying degenerative process, such as an injury, infection, or arthritis. An unknown but very small proportion of cases may progress to malignancy, and there are no known risk factors for why this may happen.

Both conditions are so unusual that most physicians will never see either one, says Eward. That may have worked against this patient, whose benign condition transformed into a dangerous malignancy.

“But that transformation was not recognized,” Eward explains. “By the time I met the patient, he had an aggressive form of cancer that had spread extensively.” Eward says that, because of the extensiveness of the metastasis, the only way to control it was through surgical means.

“Basically,” notes Eward, the patient was “skeletonized from the base of his neck down to his ribs. If this had been known to be chondrosarcoma early on,” he suggests, “the patient could have had the upper part of his shoulder joint resected, and he would have a functioning arm.”

Fortunately, the patient’s previous surgeon referred him for more treatment in time to save his life. Eward says that MRI revealed “little clumps of cancer all over the place,” which he underscores is a classic giveaway that synovial chondromatosis has transformed. A benign condition would not metastasize beyond the joint and into surrounding tissue. “If you deal with sarcomas, you just kind of recognize it,” notes Eward, adding that some nonsarcoma clinicians may not be able to readily identify the condition.

It is also possible that the prior procedures the patient underwent may have contributed to the dissemination of the cancer. Once an instrument comes into contact with a chondrosarcoma tumor, the instrument becomes contaminated and can spread the cancer cells.

More than 1 year later, the patient is doing well. Every 3 months, he undergoes scans of his lungs and meets with his team of clinicians at Duke.

“The biggest worry is that he did have spots appear in his lungs and there could be more out in his body,” explains Eward. “Maybe we got them all and he is cured. That’s what I’m hoping for.”

Eward says that patients can benefit from the accumulated experience of doctors practicing at a place like Duke. “Because sarcoma is a rare type of cancer, there’s a real benefit to having dedicated sarcoma teams at comprehensive cancer centers,” surmises Eward. “By specializing in this type of cancer, we build our experience despite it being uncommon, and we can give patients better advice and better treatment.”