Doctors Suspected Lung Cancer in a Father of Three — A Rare IgG4-RD Diagnosis Changed Everything

Misdiagnosed as Terminal Cancer After a Bike Accident

What began as a mountain biking accident nearly became a life-altering misdiagnosis for Andy Provencher, a father of three. After crashing over his handlebars in June 2020, Provencher was rushed to the emergency room with broken bones and a punctured lung. But imaging scans revealed something far more alarming — multiple masses throughout his lungs, leading doctors to suspect aggressive, terminal lung cancer.

The shocking news launched a year-long medical mystery, as repeated tests and biopsies failed to confirm cancer, yet no alternative explanation could fully account for his symptoms.

A Year of Conflicting Diagnoses and Declining Health

Over the following months, Provencher visited primary care physicians, pulmonologists, hematologists, and rheumatologists, only to receive conflicting opinions. While cancer was frequently suggested, no diagnosis was definitive.

Meanwhile, his physical condition deteriorated rapidly. He experienced severe fatigue, muscle pain, shortness of breath, and difficulty climbing stairs. Doctors eventually advised him to prepare for chemotherapy, despite the lack of a confirmed diagnosis.

A Chance Suggestion Leads to a Rare Disease Discovery

Just two weeks before beginning chemotherapy, an unexpected insight changed everything. A physician assistant studying rheumatology recognized that Provencher’s symptoms matched those of IgG4-Related Disease (IgG4-RD) — a rare immune-mediated inflammatory condition.

After consulting with a leading rheumatology specialist and undergoing targeted testing, Provencher finally received an accurate diagnosis. The moment brought instant relief after a year of uncertainty, fear, and emotional strain.

What Is IgG4-Related Disease (IgG4-RD)?

IgG4-RD is a rare autoimmune condition that can cause inflammation, tissue scarring, and organ damage throughout the body. It may affect the lungs, pancreas, liver, lymph nodes, salivary glands, eyes, and nervous system, often progressing slowly and silently.

Because there is no single blood test or biopsy that confirms IgG4-RD, patients are frequently misdiagnosed with cancer or other chronic illnesses. Many endure years of symptoms before receiving the correct diagnosis.

Breakthrough Treatment and FDA-Approved Therapy

Provencher enrolled in a groundbreaking clinical trial testing inebilizumab, a monoclonal antibody therapy designed to deplete B cells involved in immune dysfunction.

The results were transformative. Patients receiving inebilizumab experienced:

• 87% reduction in disease flare risk
• Significant improvement in symptoms
• Ability to discontinue long-term steroid use

In April 2025, inebilizumab became the first FDA-approved treatment for IgG4-Related Disease, marking a major breakthrough for patients worldwide.

Life After Diagnosis: Recovery, Advocacy, and Awareness

Now several years into treatment, Provencher reports improved energy levels and a renewed ability to enjoy time with his family. While IgG4-RD has no permanent cure, the disease can enter remission with proper treatment and monitoring.

Determined to help others avoid delayed diagnoses, Provencher and his family have become active advocates for IgG4-RD awareness, emphasizing early recognition, education, and persistence in seeking answers.

A Message for Patients Facing Uncertainty

Provencher’s experience offers a powerful reminder:
Question diagnoses, seek second opinions, and keep moving forward. Rare diseases often hide behind common symptoms, and one informed suggestion can change everything.

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