Why Are Biopsy, PET/CT, and Bronchoscopy Used for RP?

Being diagnosed with a rare condition like relapsing polychondritis (RP) can be overwhelming, especially when discussing tests to evaluate your airways. The diagnosis of RP is primarily based on your symptoms and clinical exams, but your doctor may order a biopsy, PET/CT scan, or bronchoscopy to confirm inflammation, check for hidden disease, or rule out other conditions ^[1][2]. While these tests provide valuable information, they are not all required for every patient.

Urgent Safety Warning: Airway involvement in RP can become dangerous quickly. Do not wait for a scheduled test or appointment if you develop sudden or rapidly worsening shortness of breath, new noisy breathing (stridor), an inability to speak in full sentences, blue lips, fainting, or severe chest retractions. Seek emergency medical care immediately.

Biopsy: Examining Tissue Under a Microscope

A biopsy involves numbing the area and removing a small piece of tissue to examine. You may have some pain, a risk of infection, or minor scarring afterward.

What it can show: A biopsy may support an RP diagnosis by showing chondritis (active inflammation of the cartilage) ^[3]. It is one piece of the puzzle that helps your doctor evaluate for other conditions that can resemble RP, such as granulomatosis with polyangiitis (GPA), IgG4-related disease, sarcoidosis, or lymphoma ^[4][5].

Limitations and when it may not be necessary: A biopsy is not always needed; many patients are diagnosed based on clinical symptoms alone ^[1]. Furthermore, a negative biopsy does not mean you do not have RP, as the sample might have missed the inflamed area. If a biopsy is needed, sampling the ear (auricular) cartilage is often preferred because it is much more accessible and safer than the airway, though it still carries a small risk of cosmetic changes ^[6][7]. Also, a biopsy alone cannot rule out every mimic; for example, VEXAS syndrome (a separate inflammatory condition) requires genetic blood testing ^[8].

PET/CT Scans: Mapping Metabolic Activity

A PET/CT scan involves an injection of a radioactive sugar (FDG) followed by a scan that highlights areas of high metabolic activity in the body. It does involve radiation exposure and may require you to follow specific diet instructions beforehand.

What it can show: A PET/CT scan is an adjunct test that may identify areas of cartilage inflammation that are not yet causing symptoms, such as in the ribs or airways ^[2][9]. It can also help locate a lower-risk area to biopsy if one is needed ^[7].

Limitations and alternatives: High metabolic activity on a PET scan is not specific to RP. Abnormal uptake can be caused by infections, arthritis, tumors, or other forms of vasculitis ^[10][11]. A negative scan also does not guarantee your airways are free of disease ^[6].

Non-Invasive Airway Tests: Dynamic CT and PFTs

To check if RP is affecting your breathing, doctors often start with non-invasive tests to map the airway before considering a bronchoscopy ^[12].

• Dynamic Chest CT: A CT scan (which involves radiation) taken while you breathe all the way in and out. It can show thickening of the airway walls or areas where the airway collapses during exhalation (tracheobronchomalacia) ^[12][13].
• Pulmonary Function Tests (PFTs): Breathing tests that measure airflow and lung volume.

While these tests are excellent complementary tools and are often sufficient for stable patients, they have limitations. PFTs can appear normal in early disease, and neither test allows the doctor to directly inspect the airway lining ^[14].

Bronchoscopy: Direct Airway Inspection

A bronchoscopy involves mild sedation or anesthesia and passing a flexible camera down the throat to look directly at the vocal cords, trachea, and lower airways.

What it can show: Bronchoscopy directly visualizes inflamed tissue, swelling, and airway narrowing (stenosis) that other tests might miss ^[15][16]. It is critical if you have concerning symptoms, if imaging is unclear, or if a therapeutic intervention is needed.

Risks and Safety Planning: Bronchoscopy is generally safe, but for RP patients with severe central airway disease or limited respiratory reserve, it carries higher risks. The procedure can cause bronchospasm (sudden airway tightening) or temporary airway collapse ^[12][17]. Your doctor will evaluate your overall risk using your full lung function assessment, including your oxygenation, flow-volume loops, and forced vital capacity (FVC) ^[17][18].

If you need a bronchoscopy, it should ideally be performed by an experienced multidisciplinary team, including interventional pulmonologists and anesthesiologists ^[19]. For highly selected patients with severe disease, the team may prepare specialized contingency plans, such as using positive airway pressure (CPAP) to keep the airway open. In extremely rare, life-threatening situations at specialized centers, they may plan to use ECMO (a machine that temporarily oxygenates the blood) as a rescue measure ^[20][21][22]. ECMO is a rare contingency, not a routine requirement for every RP bronchoscopy.

Comparing the Tests