Stephen Pouns broke bones, lost teeth and even his hearing over the course of several years, and no one could tell him why. The 76-year-old Houston resident eventually learned his bones had become soft and brittle because of a walnut-sized tumor tucked into soft tissue beside his artificial hip — a tumor that had been quietly secreting a hormone that was stripping his body of the phosphorus and vitamin D it needed to keep his skeleton intact.
According to the Houston Chronicle, Pouns broke his right big toe in 2016 while wrapping pipes ahead of a freeze, and that same year he lost hearing in his right ear after doctors discovered the three bones in his left ear had gone missing, requiring surgery to replace them. Two years later, an MRI showed a large fracture in his left hipbone, forcing a hip replacement. By 2020, he was in severe pain, struggling to walk, and falling repeatedly because of weakness that had crept into his body.
A Diagnosis Years in the Making
Pouns saw nearly a dozen doctors while searching for an answer, the Houston Chronicle reported, and at one point two of his teeth died outright. It wasn't until 2021 that an endocrinologist ordered blood tests that finally revealed the culprit: tumor induced osteomalacia, a rare paraneoplastic syndrome caused by a usually benign, tiny tumor that secretes a hormone called fibroblast growth factor 23, or FGF23. That hormone normally helps regulate phosphorus and vitamin D levels in the body, but in excess it impairs the kidneys' ability to absorb phosphorus and produce vitamin D, leaving bones soft and prone to breaking.
The condition is exceptionally rare. Research published in a study in Osteoporosis International notes that only approximately 2,000 unique cases of TIO have been reported worldwide, a figure consistent with the Houston Chronicle's reporting that fewer than 2,000 patients globally have ever been diagnosed with it. Diagnosis is notoriously difficult, in part because its symptoms can mimic far more common disorders, and the average time from symptom onset to diagnosis is measured in years rather than months.
Why the Disease Hides So Well
Dr. Peter Tebben, an endocrinologist and director of the Yale Bone Center at Yale School of Medicine, told the Houston Chronicle that most TIO patients are adults with a lengthy history of fractures before they're ever diagnosed, and that what causes these tumors to form in the first place remains unknown. He said a simple blood test for phosphorus can help identify possible TIO, but noted that routine blood panels don't typically include that test — part of why the disease so often slips past doctors. Tebben recommended that physicians consider TIO in patients with unexplained bone or muscle symptoms.
That symptom pattern lines up with broader research on the disease. A systematic review covering nearly 900 cases found that symptoms secondary to osteomalacia — things like proximal muscle weakness or pain — occurred in at least 89.9% of reported cases, according to a review published in PMC, with those symptoms appearing somewhat more often when tumors were located in the limbs or head and neck than in the trunk or pelvis.
Cancer Found Along the Way
Before his TIO diagnosis was even confirmed, doctors treated Pouns for colon cancer discovered in his small intestine, catching it before it spread, per the Houston Chronicle's reporting. Surgeons also removed his appendix during treatment, even though it turned out to be healthy. But his bone symptoms persisted after the cancer surgery, a sign that something else was still at work in his body.
An endocrinologist recommended an off-label drug to manage his TIO symptoms, but Pouns couldn't take it — the medication cost $40,000 a month. Unable to afford that route, he and his daughter, Dr. Katherine Pouns, a general surgeon, looked elsewhere for help. She learned about a Mayo Clinic clinical trial from a former professor, and in the summer of 2022 the family reached out to Mayo Clinic in Minnesota. The clinic initially turned Pouns down, but invited him back a few weeks later to join a different trial testing whether a specialized PET scan could pinpoint the location of his elusive tumor.
Finding the Tumor, Then Removing It
The scan worked. A radioactive diagnostic tracer administered during the 2022 trip emitted a signal near Pouns' left hip, and a separate PET scan revealed two suspicious locations in his body, according to the Houston Chronicle. Pouns made two additional trips to Minnesota for biopsy and testing before doctors confirmed the tumor's location: soft tissue beside his artificial hip, roughly the size of a walnut.
In 2023, Pouns underwent tumor-removal surgery at Mayo Clinic. Dr. Peter S. Rose, an orthopedic surgeon there who has treated about 10 TIO patients, removed the tumor along with a buffer of surrounding soft tissue, telling the Houston Chronicle that taking extra tissue is the best way to ensure complete resection. Pouns recalled that a doctor told him his bones had probably turned to dust from years of the disease eating away at them. Two days after surgery, he walked out of the hospital without a walker.
Recovery and a Return to Normal Life
The surgery cured all of Pouns' symptoms, the Houston Chronicle reported. He has since regained strength by lifting weights, returned to golfing and yard work, and has not fallen in nearly four years. Earlier ear surgery had already restored his hearing. His wife, Anne Pouns, said his nighttime pain used to prevent her from getting a full night's rest — a burden that eased once his symptoms resolved. Pouns had retired after his health deteriorated rapidly, and he said that during the worst stretch he could not pursue the activities he loved most.
Outcomes like his aren't guaranteed for every TIO patient. Some tumors can't be removed at all when they sit in delicate areas such as the spine; in those cases, the condition is managed instead with specialized phosphorus and vitamin D supplements or regular injections of a medication that blocks excess FGF23. Earlier case evidence, including a 2007 report describing a 61-year-old man left debilitated by multiple fractures and neuromuscular weakness from TIO, found that his phosphorus and vitamin D levels normalized within two days of surgery and his bone density continued improving a year later, according to findings published on Mayo Clinic's research platform. Not every patient fares as well — separate research tracking 117 surgically treated TIO cases found that over a median follow-up of 12 months, 19 patients remained uncured, including five with local recurrence and two with distant metastases.
Dr. Katherine Pouns told the Houston Chronicle that patients facing a similarly elusive diagnosis should keep pushing doctors until they find an answer. For her father, that persistence — and a clinical trial that almost didn't happen — turned years of broken bones and unexplained pain into a diagnosis, a surgery, and a return to the ordinary rhythms of retirement in Houston.
