Mesothelioma with clear cell features: an ultrastructural and immunohistochemical study of 20 cases

Our plain-English summary of Mesothelioma with clear cell features: an ultrastructural and immunohistochemical study of 20 cases, by N.G. Ordóñez (Human Pathology, 2005).

The study

• Author: N.G. Ordóñez
• Journal: Human Pathology
• Published: 2005;36(5):465-73
• Cited by: 36 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Mesotheliomas with clear cell morphology are rare and only a few individual case reports have been documented in the literature. The author reports a series of 20 epithelioid mesotheliomas with clear features, 17 of which originated in the pleura and 3 in the peritoneum. Eighteen of the patients were men and 2 were women. Twelve patients had a history of asbestos exposure. Electron microscopy and special histochemical stains demonstrated that the cytoplasmic clearing seen in hematoxylin and eosin-stained sections resulted from multiple factors that can occur either singly or in combination. The most frequent cause of the cytoplasmic clearing was the accumulation of large amounts of intracytoplasmic glycogen. Another but somewhat less common factor was the accumulation of large amounts of lipid, which occurred alone or with glycogen. Other less common causes were marked mitochondrial swelling, the presence of numerous intracytoplasmic vesicles, and a large number of intracytoplasmic lumens. The value of immunohistochemistry in helping to distinguish epithelioid mesotheliomas from some carcinomas with clear cell morphology is emphasized. In addition, it was determined that because electron microscopy was decisive in establishing the cause of the cytoplasmic clearing in most of the cases, tissue for electron microscopy should routinely be procured for ultrastructural studies.

In plain English

This study described 20 epithelioid mesotheliomas from one Texas cancer center whose cells looked clear under the microscope. Seventeen arose in the pleura and 3 in the peritoneum; 18 of the patients were men. Twelve had a history of asbestos exposure, with no details given. The author used special stains and, in 15 cases, electron microscopy to explain the clear look, and immunohistochemistry to check the diagnosis. Glycogen, a stored sugar, was the most frequent cause, shown by staining in 14 cases. Large amounts of fat (lipid) came next. Swollen mitochondria were the main cause in one case and appeared with lipid in another; many small sacs (vesicles) explained the clearing in one case. In another case, tiny cavities inside cells contributed alongside glycogen and widened spaces between cells. Every case tested was positive for the mesothelioma markers calretinin (16 of 16), keratin 5/6 (13 of 13) and mesothelin (5 of 5). The author concluded that the clearing has several causes and that immunohistochemistry helps distinguish these tumors from clear cell carcinomas. The author also recommended routinely saving tissue for electron microscopy.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case series: pathology study (light microscopy, special stains, immunohistochemistry, electron microscopy) of 20 cases from one hospital's files
• Who was studied: 20 patients with epithelioid mesothelioma showing clear cell features, from the files of the Department of Pathology at The University of Texas MD Anderson Cancer Center (Houston): 18 men and 2 women, aged 55 to 86 years (mean 67); 17 pleural and 3 peritoneal tumors
• Exposure: History of asbestos exposure in 12 of the 20 patients and smoking in 9. No fiber type, job or dose is given, and exposure was not analyzed further.
• Main results:
  • The mesotheliomas arose in the pleura in 17 cases and in the peritoneum in 3
  • PAS stain showed glycogen in 14 of the 20 cases. In 5 of these, glycogen was considered the only cause of the clear appearance.
  • Electron microscopy (done in 15 cases) showed large amounts of glycogen in 7 cases, glycogen and lipid in 3, and lipid alone in 3
  • In one case (case 10), swelling of the mitochondria was the main cause of the clear appearance
  • In a second case (case 11), Table 2 lists lipid and swollen mitochondria as the electron microscopy findings associated with the clear appearance
  • In one case (case 3), the clear appearance was due to large numbers of vesicles
  • In one case (case 19), many intracytoplasmic lumens, widened spaces between cells and glycogen were all contributing factors to the clear appearance
  • All cases tested were positive for calretinin (16/16), keratin 5/6 (13/13) and mesothelin (5/5)
  • WT1 was positive in 8 (89%) of 9 cases tested. Thrombomodulin was positive in 3 of 5 cases tested.
  • No case tested was positive for the markers CEA, B72.3, CD15, MOC-31, TTF-1, Ber-EP4, RCC Ma or p63
  • Follow-up was available for 9 of the 20 patients. Five died of disease 3 to 40 months (mean 16) after diagnosis, and 4 were alive with disease 1 to 23 months (mean 11) after diagnosis.
• The authors' conclusion: The author concluded that the clear appearance in these mesotheliomas has several causes, alone or combined, most often glycogen. Immunohistochemistry helps distinguish these tumors from carcinomas with clear cells. Because electron microscopy was decisive in most cases, tissue should routinely be saved for it.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma, Peritoneal mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Epithelioid, Pleura, Peritoneum, Asbestos Exposure, Immunohistochemistry, Carcinoma.

Related studies

• Mesothelioma with rhabdoid features: an ultrastructural and immunohistochemical study of 10 cases — N.G. Ordóñez (2006)
• Malignant biphasic peritoneal mesothelioma in a child: fine-needle aspiration cytology, histopathology, and immunohistochemical features along with review of literature — S.K. Arora, R. Srinivasan, et al. (2012)
• Are oestrogens and genetic predisposition etiologic factors in the development of clear cell carcinoma of the peritoneum? — R. Wuntakal, A. Lawrence (2013)
• Clear cell mesothelioma presenting as an incarcerated abdominal hernia — N.G. Ordóñez (2005)
• Lymphohistiocytoid mesothelioma: a clinical, immunohistochemical and ultrastructural study of four cases and literature review — D.X. Yao, J. Shia, et al. (2004)
• Two cases of malignant peritoneal mesothelioma without asbestos exposure: cytologic and immunohistochemical features — Y. Kinoshita, K. Takasu, et al. (2013)

Browse more research in Human Pathology, or return to medical research.