Pleura & peritoneum
Pleura mesothelial tumors
Mesothelioma (pleura)-epithelioid
Author: Vaidehi Avadhani, M.D.
Last author update: 1 November 2013
Last staff update: 28 February 2023
Copyright: 2003-2023, PathologyOutlines.com, Inc.
PubMed Search: Epithelioid mesothelioma[TIAB] pleural
See Also: Mesothelioma
Table of Contents
Definition / general | Case reports | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Electron microscopy description | Differential diagnosis | Board review style question #1 | Board review style answer #1Cite this page: Avadhani V. Mesothelioma (pleura)-epithelioid. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pleuramesotheliomaepithelioid.html. Accessed June 4th, 2023.
Definition / general
- Most frequent histologic type of malignant mesothelioma
Case reports
- 73 year old man with bilateral pleural effusions, lung nodules and pleural thickening (Case of the Week #476)
Microscopic (histologic) description
- Composed of oval, polygonal or cuboidal cells, with multiple secondary patterns:
- Tubulopapillary:
- Characteristic papillary growth pattern
- Tumor cells with round nuclei, moderate amounts of eosinophilic cytoplasm and conspicuous nucleoli
- Elongated tubular structures may also be seen
- Must distinguish from micropapillary pattern, which has a poorer prognosis
- Tubulopapillary:
- Other patterns:
- Acinar: elongated or branching gland-like lumina lined by relatively bland cuboidal cells
- Adenomatoid
- Adenoid cystic: cribriform and tubular patterns separated by fibrous stroma
- Clear cell: mesothelial cells with clear cytoplasm
- Deciduoid: sheets of large polygonal cells with abundant glassy cytoplasm, round vesicular nuclei and prominent nucleoli
- Micropapillary: has higher incidence of lymphatic invasion
- Pleomorphic: marked nuclear pleomorphism; if this component is > 10%, has an adverse prognosis
- Rhabdoid: dyscohesive cells with abundant eosinophilic cytoplasm, eccentric nuclei, prominent nucleoli; variable eosinophilic cytoplasmic inclusion
- Signet ring cell: clusters or sheets of cells with cytoplasmic vacuoles
- Small cell: very rare; uniform small round cells with high N:C ratio
- Solid
- Trabecular
Microscopic (histologic) images
Contributed by Jijgee Munkhdelger, M.D., Ph.D. and Andrey Bychkov, M.D., Ph.D.
Low power
Infiltration through the membrane
Multinucleation
High power
Epithelioid mesothelioma EMA
Epithelioid mesothelioma immunoprofile
Case #476
CK5/6
MOC31
WT1
BerEP4
Cytology description
- Papillary epithelial type:
- Papillary fragments and cohesive cell clusters
- Moderate amount of cytoplasm
- Round to ovoid nuclei, prominent nuclei
- Psammoma bodies may be seen (Cancer Cytopathol 2013;121:703)
- Cohesive epithelioid type:
- Cohesive groups of cells
- Nuclei round or oval with some pleomorphism
- Eccentrically located nuclei occasionally with coarse chromatin
- Multinucleation is common
- Variable mitotic figures
- Asbestos bodies maybe seen
Positive stains
- Calretinin: both nuclear and cytoplasmic staining; useful to distinguish mesothelioma and lung adenocarcinoma
- Keratin 5 / 6: expressed in epithelioid mesothelioma but negative in sarcomatoid mesothelioma
- Podoplanin (D2-40): membranous and apical staining; may be expressed in squamous cell carcinoma of lung and serous carcinoma, synovial sarcoma and angiosarcoma
- WT1: useful to distinguish mesothelioma from renal cell carcinoma and squamous cell carcinoma (Hum Pathol 2013;44:1)
Negative stains
- TTF1 and Napsin A: positive in lung adenocarcinoma
- PAX8: positive in tumors of Müllerian origin
- GATA3 / GCDFP-15 / mammaglobin: positive in breast cancers
- MOC31, BerEp4, CEA: positive in adenocarcinoma
- Claudin4 may distinguish epithelioid mesothelioma (negative) from metastatic carcinoma to serosal membranes (Am J Clin Pathol 2013;139:611)
Electron microscopy description
- Very long, thin apical microvilli that do not have a glycocalyx
- Adenocarcinomas have shorter microvilli, have a glycocalyx and perinuclear tonofilament bundles
Differential diagnosis
Board review style question #1
Which set of antibodies is useful for distinguishing pleural malignant mesothelioma from lung adenocarcinoma?
A. WT1, CA125, BerEP4 (EpCAM)
B. CA125, BerEP4, Calretinin
C. BerEP4, Calretinin, AE1/AE3
D. WT1, BerEP4, Calretinin
E. WT1, BerEP4, AE1/AE3
A. WT1, CA125, BerEP4 (EpCAM)
B. CA125, BerEP4, Calretinin
C. BerEP4, Calretinin, AE1/AE3
D. WT1, BerEP4, Calretinin
E. WT1, BerEP4, AE1/AE3
Board review style answer #1
D. WT1 and calretinin are specific for mesothelial cells and BerEP4 is specific for lung adenocarcinoma. CA125 and AE1/AE3 are immunoreactive in both mesothelioma and adenocarcinoma.
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Reference: Mesothelioma (pleura) - epithelioid
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Reference: Mesothelioma (pleura) - epithelioid
