Why do a lung biopsy for benign lesions?

Transthoracic needle biopsy of lung lesions is a well-established procedure for the diagnosis of lung lesions. The literature focuses on the diagnosis of malignant lesions with an often reported accuracy rate of more than 90%. Experience showed that biopsy can identify sometimes incidentally, also benign lesions. There are many reasons why a biopsy is performed for a "benign lesion." First of all, it may be an unexpected diagnosis, as some benign pathologies may have misleading presentations, that are very similar to lung cancer, otherwise the reason is only to make a diagnosis of exclusion, which leads to the benign pathology already being considered in the differential diagnosis.

This study was designed as a retrospective single-center study. We selected from our database all the lung biopsies performed under CT guidance, from 2015 to 2019 and retrospectively analysed the histological data. We selected only benign lesions describing the imaging feature and differential diagnosis with lung malignancy.

In our patient population, among the 969 of them that underwent biopsy, we identified 93 benign lesions (10%). Hamartomas, granulomas, slow-resolving pneumonia and cryptogenic organizing pneumonia are the pathologies that most frequently can misinterpratedas lung cancer.

In this brief report we want to show the percentage and type of benign lesions that are found in our lung trans-thoracic biopsy population. Among these, we identified the three most frequent benign lesions that most frequently enter the differential diagnosis with lung malignant lesions describing the classic and atypical imaging findings.