Mountain-bike crash leads to rare immune disease diagnosis after cancer scare
After a 2020 bike accident, Andy Provencher was misdiagnosed with aggressive lung cancer before a rheumatologist identified his true condition as IgG4-related disease.
In June 2020, Andy Provencher’s mountain-bike crash resulted in broken bones, a punctured lung and an emergency-room report of numerous lung masses that doctors labeled an aggressive form of cancer. Over the following year, multiple specialists could not reach a definitive diagnosis, and Provencher’s health declined dramatically. A rheumatology-focused physician assistant introduced the possibility of IgG4-related disease, prompting a referral to Dr. John Stone, a leading expert in the condition.
After targeted testing, Stone diagnosed Provencher with IgG4-RD and enrolled him in a trial of the B-cell-depleting drug inebilizumab. The trial’s results led to the drug’s FDA approval in April 2025, and Provencher now reports significant improvement while continuing treatment. He and his wife Katharine have joined the IgG4ward! Foundation to promote education and earlier detection of the disease.