Diagnostic value of biopsy sampling in predicting histology in patients with diffuse malignant pleural mesothelioma

Abstract

Background The classification of diffuse malignant mesothelioma into epithelioid, biphasic, and sarcomatoid types is based on histologic patterns. The diagnosis is made on biopsies, and because of intratumoral heterogeneity, they may not be representative of the entire tumor. The number and volume of biopsies needed to reach diagnostic accuracy in diffuse malignant mesothelioma and their prognostic value remain unclear. Methods This study examined 759 consecutive patients with pleural diffuse malignant mesothelioma treated by pleurectomy/decortication or extrapleural pneumonectomy for the presence of epithelioid and/or sarcomatoid histology and classified both the presurgery biopsies (core‐needle or thoracoscopic) and surgical resection specimens. The number and volume of biopsies were correlated with pre‐ and postsurgery histologies and overall survival. Results Diffuse malignant mesothelioma was classified as epithelioid (76%), biphasic (18%), sarcomatoid (5%), or indeterminate (1%) in biopsies and as epithelioid (64%), biphasic (32%), and sarcomatoid (4%) in surgical resection specimens (overall concordance, 80.6%). The positive likelihood ratios were 2.4, 13.6, and 90.1 for biopsies with epithelioid, biphasic, and sarcomatoid histologies, respectively. Concordant histologies between biopsies and resections were associated with a higher number of biopsies (median tissue blocks for concordant histologies vs discordant histologies, 3 vs 2; P < .002) but were less associated with a higher volume (median, 1.2 vs 1.1 cm3; P = .06). In a multivariate analysis, overall survival was independently predicted by histology in the resection specimen (P < .0001) but not in the biopsy (P = .09). Conclusions In contrast to epithelioid histology, sarcomatoid histology in biopsies is highly accurate. Despite intratumoral heterogeneity, the accuracy of histologic classification increases with the number of tissue blocks examined, emphasizing the diagnostic value of extensive sampling by presurgery biopsies.

EURACAN/IASLC Proposals for Updating the Histologic Classification of Pleural Mesothelioma: Towards a More Multidisciplinary Approach

“…A higher number of tissue blocks in biopsy specimens have been shown to provide better concordance with tumor subtype in resection specimens, as well as thoracoscopic biopsy specimens showing better concordance than needle biopsy specimens. 61 There may also be value in the assessment of tumor volume derived from CT scans as a prognostic factor and maximum PET avidity for targeting particularly active areas that may have prognostic relevance.…”

Diagnostic yield of Xpert MTB/RIF on contrast-enhanced ultrasound-guided pleural biopsy specimens for pleural tuberculosis

“…Pleural mesothelioma is a malignant pleural disease that is difficult to diagnose by minimally invasive means. Even video-assisted multipoint biopsies have a certain rate of missed diagnosis (Chirieac et al, 2019). The three cases of mesothelioma in this study were all diagnosed by thoracoscopic biopsy, but the ultrasonic-guided biopsy pathology also showed malignant lesions.…”

Update on Diagnosing and Reporting Malignant Pleural Mesothelioma

“…The 2015 WHO classification of pleural tumors divides diffuse malignant mesothelioma into three main histological subtypes: Epithelioid (60%-80%), sarcomatoid (<10%), and biphasic (10%-15%). The relative frequency is higher for biphasic subtypes and lower for sarcomatoid subtypes in surgical specimens compared to pre-resection biopsies, indicating the importance of sampling in accurate classification of malignant pleural tumors (7). It is important to distinguish between these subtypes because of stage-dependent differences in therapeutic strategies and differences in average lengths of survival.…”