He was diagnosed with lung cancer, it was in fact a rare disease which benefited from a revolutionary treatment

He was diagnosed with lung cancer, it was in fact a rare disease which benefited from a revolutionary treatment
In 2020, after a fall from a mountain bike, doctors accidentally discovered masses in Andy Provencher’s lungs. They tell him he has terminal cancer. However, a year later, a diagnosis of a rare disease will change everything. Deciphering this incredible story with Dr Gérald Kierzek.

The media CBS reports the extraordinary story of Andy Provencher, father of three children. After a bicycle accident, he thought his broken bones would be his only worry.

But the examination in the emergency room reveals a much darker reality. “Your lungs are littered with masses. This looks like a very aggressive form of lung cancer.”the doctors tell him. Then begins a year-long medical wandering, where the biopsies contradict the scans, leaving Andy in extreme anguish.

IgG4-RD: the “chameleon” disease that mimics tumors

As he prepares to begin chemotherapy, Andy meets a rheumatology medical assistant. He brings up an unexpected avenue: immunoglobulin G4-related disease (IgG4-RD).

“IgG4-RD is a rare immune disease characterized by chronic fibro-inflammatory inflammation that can affect almost any organ, forming tumor lesions, inflammation and scarring. explains Dr. Gérald Kierzek, emergency physician and medical director.

In Andy’s case, his lungs were affected by the disease, perfectly mimicking a malignant tumor.

Why is the diagnosis so difficult to make?

Andy’s story illustrates the complexity of this pathology. Doctors initially suspected cancer because “scans showed multiple aggressive lung masses, perfectly mimicking a malignant tumor” specifies Dr Gérald Kierzek.

Additionally, IgG4-RD progresses slowly and damages tissues even before the first signs appear. The symptoms are often vague: fatigue, weight loss, joint pain or shortness of breath.

“The disease often progresses with tumor lesions that are difficult to distinguish from cancers without expert examination” adds the doctor.

A therapeutic revolution: the arrival of inebilizumab

For a long time, the standard treatment was based solely on corticosteroids. “Management begins with high-dose corticosteroids to reduce inflammation, often followed by maintenance therapy. recalls Dr. Kierzek.

Andy had the chance to join a clinical trial allowing him to benefit from inebilizumab, a monoclonal antibody targeting B cells (CD19). The results were spectacular: the risk of disease flare-up was reduced by 87% over one year in treated patients.

In April 2025, this treatment became the first drug specifically approved for IgG4-RD, offering concrete hope for avoiding irreversible after-effects.

Living with a chronic illness without a cure

Today, Andy has regained the energy to play with his children, even though the internal scars left by the disease before diagnosis are permanent.

“It is crucial to understand that while treatment works, it is not a complete cure“insists Dr. Gérald Kierzek.”The disease can go into remission but is not cured and requires chronic monitoring to prevent relapses and irreversible fibrosis.”

For Andy and his wife, Katharine, the challenge now is to inform so that other patients do not wait years for a diagnosis that could save their lives.