Chirieac LR, Hung YP, Foo WC, et al. - Researchers intended to gain clarity about the number and volume of biopsies required to reach diagnostic accuracy in diffuse malignant mesothelioma, as well as their prognostic significance. Participants were 759 consecutive patients treated by pleurectomy/decortication or extrapleural pneumonectomy. These patients were examined for the presence of epithelioid and/or sarcomatoid histology. Both the presurgery biopsies (core-needle or thoracoscopic) and surgical resection specimens were grouped. They examined the correlation of the number and volume of biopsies with presurgery and postsurgery histologies and overall survival. Findings revealed high accuracy of sarcomatoid histology in biopsies vs epithelioid histology. With the number of tissue blocks examined, an increase in the accuracy of histologic classification was seen, although intratumoral heterogeneity was evident. This highlights that extensive sampling by presurgery biopsies has diagnostic value.