Guidelines for Pathologic Diagnosis of Malignant Mesothelioma 2017 Update of the Consensus Statement From the International Mesothelioma Interest Group

Abstract

- There was discussion and consensus opinion regarding guidelines for (1) distinguishing benign from malignant mesothelial proliferations (both epithelioid and spindle cell lesions), (2) cytologic diagnosis of MM, (3) recognition of the key histologic features of pleural and peritoneal MM, (4) use of histochemical and immunohistochemical stains in the diagnosis and differential diagnosis of MM, (5) differentiating epithelioid MM from various carcinomas (lung, breast, ovarian, and colonic adenocarcinomas, and squamous cell and renal cell carcinomas), (6) diagnosis of sarcomatoid MM, (7) use of molecular markers in the diagnosis of MM, (8) electron microscopy in the diagnosis of MM, and (9) some caveats and pitfalls in the diagnosis of MM. Immunohistochemical panels are integral to the diagnosis of MM, but the exact makeup of panels employed is dependent on the differential diagnosis and on the antibodies available in a given laboratory. Depending on the morphology, immunohistochemical panels should contain both positive and negative markers for mesothelial differentiation and for lesions considered in the differential diagnosis. Immunohistochemical markers should have either sensitivity or specificity greater than 80% for the lesions in question. Interpretation of positivity generally should take into account the localization of the stain (eg, nuclear versus cytoplasmic) and the percentage of cells staining (>10% is suggested for cytoplasmic and membranous markers). Selected molecular markers are now being used to distinguish benign from malignant mesothelial proliferations. These guidelines are meant to be a practical diagnostic reference for the pathologist; however, some new pathologic predictors of prognosis and response to therapy are also included.

Mesotheliomas in Genetically Engineered Mice Unravel Mechanism of Mesothelial Carcinogenesis

“…Epithelioid and sarcomatoid categories have several secondary growth patterns as reported by Hussain et al [12]. …”

Management and Survival of Pleural Mesothelioma: A Record Linkage Study

“…Online supplementary Table 2 shows the validation study of our selection algorithm on 68 subjects for whom we could check and validate the diagnosis through immunohistochemical pathology report [16] at the “Ospedali Riuniti” hospital, Bergamo. Of the 38 (56%) patients included in our cohort, 36 (95%) were confirmed mesothelioma cases.…”

“…This applies to record linkage studies as well. It is possible that misdiagnosis of mesothelioma has occurred if no immunohistochemical verification, requested for diagnosis confirmation, was performed [10, 16]. The present study is based on the Lombardy region health care administrative databases.…”

Diagnostic yield of pleural fluid cytology in malignant effusions: an Australian tertiary centre experience

“…Nonadenocarcinoma NSCLC (NSCLC not specified, NSCLC with neuroendocrine differentiation and squamous cell carcinoma) also demonstrated high sensitivity; however, with only five cases in our cohort this should be interpreted with caution. 26,27 Repeated cytological analysis with a second sample only modestly improved the accuracy (by 4.3% to 90.2%) and sensitivity (by 7.7% to 75.4%) of pleural fluid cytology for MPE diagnosis, with most cases diagnosed on a second sample being less common tumour types. 23 Our finding regarding sensitivity is consistent with other studies reporting significantly lower sensitivity for detection of mesothelioma (range 27-48%).…”