Extrathoracic Mesothelial Proliferations and Their Mimics

Abstract

Mesothelial proliferations, either reactive or neoplastic in nature, often pose difficult diagnostic dilemmas. Electron microscopy continues to be a gold standard in the identification of mesothelial differentiation. However, it is very common to apply long panels of antibodies for that purpose. In most cases, light microscopy and immunohistochemistry will solve the problem. However, the definitive, specific, and sensitive immunohistochemical marker is still lacking. This is particularly true in peritoneal and testicular mesothelial tumors, in which common embryologic origin with epithelial elements results in overlapping immunohistochemistry and morphology. The particularities of peritoneal and testicular mesothelial proliferations, and the main tumors that may mimic them in these sites, as well as the value and limitations of immunohistochemistry and electron microscopy in their differential diagnosis are the subject of this review.

KEYWORDS:

• electron microscopy
• immunohistochemistry
• mesothelioma
• mesothelium
• ovarian tumors
• peritoneal tumors
• serosal carcinoma
• serosal neoplasms
• testicular tumors

Notes

To Patricia Troncoso, Anais Malpica, and Pheroze Tamboli, from the Department of Pathology at the University of Texas M.D. Anderson Cancer Center, Houston, Texas, for the help in the study of their files. To Esther Oliva, from the Department of Pathology of the Massachussetts General Hospital, Boston, Massachussetts, and Mahul Amin, from the Department of Pathology, Emory University Hospital, Atlanta, Georgia, for providing examples of some unusual testicular and peritoneal tumors. To Sergi Serrano, from the Department of Pathology, Hospital del Mar and Autonomous University of Barcelona, and Daniel Dallari, from the Institut de Citologia i Histopatologia, Barcelona, Spain, for providing some of the cases used in this review.