The concept of mesothelioma in situ, with consideration of its potential impact on cytology diagnosis

Progression of mesothelioma in situ to invasive disease 4 years and 10 months after initial diagnosis

“…6,7 In a recent publication we noted that over 4 years later, there had been no progression in this case. 8 This patient had originally presented with recurrent pleural effusions, which were not overly cellular but showed mild cytological atypia and deletion of BAP1, and some papillary proliferations in a later sample. Radiology at the time showed pleural effusion, with no plaques and no nodularity (Fig.…”

Inflammation of the Pleural Cavity: A Review on Pathogenesis, Diagnosis and Implications in Tumor Pathophysiology

“…After these observations, the mesothelioma in situ is for the first time included in the current WHO classification, and the essential criteria for its diagnosis are: non-resolving pleural effusion, no thoracoscopic or imaging evidence of tumor, single layer of mesothelial cells on the surface without invasive growth, and loss of BAP1 and/or MTAP and/or CDKN2A homozygous deletion, and multidisciplinary discussion of the diagnosis. Despite these guidelines, there still are inconsistencies in how the diagnosis is made even among experts, as shown in a recent survey of 34 pathologists [92]. Almost 70% of them had made or suggested the diagnosis of MIS in their practice; the diagnosis had been made between 0 and >20 times by individual pathologists, but the diagnosis was generally rare (two cases in a database of 4677 specimens and seven in a database of 3214 cases), and made the last two to four years, in comparison to the databases that spanned 40 years of practice [92].…”

The highlights of the 15th international conference of the international mesothelioma interest group – Do molecular concepts challenge the traditional approach to pathological mesothelioma diagnosis?

“…Still, it is unclear how will that translate to pathological practice-should every bulla resection after pneumothorax be subjected to ancillary testing? Clinical practice and thresholds for testing vary [11]. Pathologists mentioned the impact of the utility of BAP1 and CDKN2A gene loss for early diagnosis in a number of presentations and specifically addressed the potential impact of the use of these findings in cytology diagnosis.…”