Its cause is unknown - but patients are known to have abnormal growths of blood vessels that can eventually break down bone. Additional tests of the Scottish woman showed blood vessel growths were replacing her bone tissue. Photo / BMJ Case Reports
The patient first sought help when a niggling pain in her shoulder wouldn't go away - but medics were baffled.
Scans initially appeared to show a lesion on her humerus, which led them to believe she had cancer. But tests came back negative.
Another biopsy revealed a benign blood vessel tumour several months later.
The woman continued to be plagued by pain and swelling in her arm over the course of the next year. But doctors were still unable to pinpoint what was causing it.
Scans taken 18 months after the woman initially visited the hospital led the doctors to consider a diagnosis of Gorham-Stout disease.
They consulted specialists in Birmingham who confirmed the disease.
The doctors wrote in the journal: "While the condition is considered benign, the prognosis is uncertain."
They added it has 'potential fatal complications that include disease spread to the vertebrae, leading to pleural effusion and quadriplegia'.