Pleura & peritoneum
Pleura mesothelial tumors
Atypical mesothelial hyperplasia (pleura)
Author: Vaidehi Avadhani, M.D.
Last author update: 1 July 2013
Last staff update: 17 July 2024
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: Atypical mesothelial hyperplasia pleural
Table of Contents
Definition / general | Terminology | Sites | Etiology | Clinical features | Radiology description | Case reports | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Differential diagnosisCite this page: Avadhani V. Atypical mesothelial hyperplasia (pleura). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pleuraatypicalmesohyper.html. Accessed December 1st, 2024.
Definition / general
- Worrisome proliferations of mesothelial cells that are not unequivocally malignant are termed atypical mesothelial proliferation or atypical mesothelial hyperplasia
Terminology
- Pseudoneoplastic lesion of the pleural surface
- Are actually reactive mesothelial proliferations, associated with both benign and malignant conditions
Sites
- Any mesothelial surface, including pleura, peritoneum, tunica, etc.
Etiology
- Associated with anemia, bronchogenic carcinoma, cirrhosis, connective tissue diseases, pneumothorax (recurrent), viral infections
Clinical features
- History of pleural effusion or ascites, fluid may be hemorrhagic
Radiology description
- Description of pleura on imaging or pleuroscopy helps differentiate benign and malignant mesothelial proliferations
- Circumferential pleural thickening and nodular pleural thickening are highly suggestive of malignancy (Arch Pathol Lab Med 2012;136:1217)
Case reports
- 49 year old man with malignant mesothelioma eight years after a diagnosis of atypical mesothelial hyperplasia (J Clin Pathol 1999;52:535)
- Mesothelial hyperplasia with reactive atypia (Diagn Cytopathol 2000;22:113)
Microscopic (histologic) description
- Identification of neoplastic invasion is definitive criteria for diagnosis of malignant mesothelioma
- Finding of mesothelial cells in fat makes the proliferation malignant
- Challenges and controversies in diagnosis of mesothelioma discussed at J Clin Pathol 2013;66:847
Microscopic (histologic) images
Images hosted on other servers:
Pleural patches - no invasion
Various immunostains - no invasion
Cytology description
- Criteria are defined for malignant mesothelioma (high specificity - 99% when all criteria are fulfilled); refer to malignant mesothelioma
- Cytology of atypical mesothelial cells:
- Mesothelial cells in large groups
- Cell groups with scalloped borders
- Nuclear hyperchromasia
- High N:C ratio
- Coarse chromatin
- Prominent nucleoli
- Diagnostic problems in serous effusions discussed at Diagn Cytopathol 1998;19:131
Positive stains
- All active mesothelial proliferations, benign or malignant, are pankeratin+
- EMA, GLUT1 and IMP3 can be positive in both benign and malignant mesothelial proliferation so cannot be used to differentiate reliably
- Homozygous deletion of p16 / CDKN2A demonstrated by FISH may be specific for malignant proliferations
- p16 FISH staining usually negative in benign proliferations, 59% sensitive for malignant mesothelioma (Am J Clin Pathol 2011;135:619)
Differential diagnosis
- Adenocarcinoma: positive for CEA, CD15, B72.3, BerEp4
- Malignant mesothelioma: epithelioid, sarcomatoid, well differentiated papillary mesothelioma
- Site specific tumors: related to the peritoneum, tunica, etc.
