Lung Biopsy in UIP

When a biopsy is planned, review of the HRCT will show appropriate sites. The surgeon is directed towards areas of ground-glass opacity and away from honeycombing, reticular change, or traction bronchiectasis. Two sites should be biopsied rather than only one, in case one is non-diagnostic. Although the tips of the lingula or middle lobe are technically easy to biopsy, they may have unrelated changes, but inclusion of a generous amount of tissue adjacent to the tips is satisfactory. A portion of the biopsy should be taken for culture and the remaining portion then given to the pathologist unfixed. Any special procedures requiring special fixatives or frozen tissue must be agreed upon in advance. Otherwise, the tissue is fixed in 10% formalin for routine sectioning.

Biopsy site

Another HRCT slice from the current patient shows optimal sites for biopsy in the right lung between the arrows. This region shows some ground-glass attenuation and borders the major fissure.

Dried Normal Left Lung

For thoracoscopic biopsies, the lung collapses as the chest is opened. Biopsies are usually taken from edges or tips of lobes, avoiding the upper part of the major fissure where hilar structures are in close proximity medially. A generous portion of lung tissue adjacent to the tip will allow the pathologist to focus on disease and ignore non-specific changes at the very tip. If necessary, any surface can be selected by a forceps, stapled, and removed.

After staples have been removed, the pathologist gently distends the unfixed specimen with formalin via a syringe with a fine needle. The specimen is then immersed in formalin until it is fixed. This procedure prevents alveolar collapse that can resemble fibrosis.

Special Stains

In addition to routine H&E stains, some of the sections should be stained with the elastic van Gieson (or the equivalent pentachrome) stain to delineate vessels and airways and to differentiate recent (pink) and old (red) fibrosis (arrows).

Iron stain

Stains for iron should be performed on biopsies with a diagnosis of UIP to detect the presence of asbestos bodies. The photo shows several beaded structures, which are asbestos fibers (note narrow core) that have been given an iron-protein coat in a macrophage.

Finding one body in 2 cm2 of tissue in a patient with UIP is highly suggestive of asbestosis, provided that a history of asbestos exposure can be obtained [1]. Rarely, the iron coated, ferruginous body has a core of another mineral.

Reference

1.Warnock M. Lung asbestos burden in shipyard and construction workers with mesothelioma: comparison with burdens in subjects with asbestosis or lung cancer. Environ Res 1989; 50:68-85.

Clinical summary Discussion

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