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The various forms of interstitial lung disease (ILD) can be impossible to tell apart without a biopsy. There's too much overlap between them in their appearance on imaging (high-resolution chest CT), and in clinical features.
A surgical lung biopsy is the standard in such cases. For many patients and physicians, though, the risk and discomfort from surgery is too high a hurdle. Many, perhaps most patients with ILD forgo surgical lung biopsy and opt for empiric treatment with immune modulating therapy, or observation.
Cryobiopsy is a less-invasive technique performed during bronchoscopy that could someday change that equation. In cryobiopsy, a probe is deployed through the bronchoscope and placed near the chest wall. The probe is cooled for a few seconds, freezing and causing the lung tissue around it to stick to the probe. The scope and probe are removed, and bleeding is controlled using a balloon occlusion catheter.
Cryobiopsy obtains larger tissue samples with less avulsion artifact compared to forceps transbronchial biopsy, which is inadequate for diagnosis of most ILD.
In an oral presentation at the annual European Respiratory Society, Benjamin Bondue, MD presented early findings of a prospective study for the use of cryobiopsy to identify the subtype of ILD.
Twenty-four patients with undetermined subtypes of ILD underwent cryobiopsy, and 16 of them were diagnosed with a specific treatable type of ILD (besides nonspecific interstitial pneumonitis or NSIP). Almost 80% therefore achieved a diagnosis while avoiding surgical lung biopsy.
The truth about ILD, of course, is that even a pathologic diagnosis can lack specificity or confidence. "Interdisciplinary consensus"; i.e., a pathologist, radiologist, and pulmonologist talking each other into a diagnosis, is the highest standard. Few patients get that; many don't even get a specialized lung pathologist reading their case. Once that diagnosis is made, it's considered the reality. But is it?
Only 5 of the 24 patients in this study underwent surgical lung biopsy after cryobiopsy, and two of the three with an "NSIP" diagnosis after cryobiopsy were reclassified as idiopathic pulmonary fibrosis.
Pneumothorax is common after cryobiopsy, occurring in 20% of patients in an earlier series of 241 patients.
Five patients here experienced pneumothorax (two requiring chest tubes). One patient had severe bleeding. There were no deaths.
Don't expect cryobiopsy to catch on widely any time soon. But the procedure does represent a potential alternative to surgical lung biopsy, which is often deferred due to its morbidity and risks.