Electron Microscopy Remains the Gold Standard for the Diagnosis of Epithelial Malignant Mesothelioma: A Case Study

Abstract

This is a case of idiopathic epithelial malignant mesothelioma in a 47-year-old mechanic. The advent of a large battery of immunochemical markers has provided new tools for the diagnosis of mesothelioma in recent years, however, immunostaining can often be misleading or inconsistent, as demonstrated in the current case. This report highlights the lasting utility of electron microscopy in the diagnosis of mesothelioma. Ultrastructural features of epithelial mesothelioma were discernable using electron microscopy even on somewhat poorly preserved chest wall biopsy specimens from paraffin blocks. These images, combined with immunostains and a fiber analysis from the lungs, allowed for a final diagnosis of a non-asbestos related malignant epithelial mesothelioma in this patient.

Detection of Anaplastic Lymphoma Kinase-Rearranged Mesothelioma Cells in Ascites by Companion Diagnostics

“…Our TEM analyses of malignant mesothelioma cells were important for the definitive diagnosis. There were 3 cardinal findings: (1) long, fine, dense microvilli; (2) welldeveloped intercellular desmosomes; and (3) intracytoplasmic tonofilaments [10]. The microvilli in our case were short and less dense than in typical mesothelioma, but the other 2 features were actually quite similar.…”

“…These histological and IHC findings excluded metastatic lung adenocarcinoma, germ cell tumor, and high-grade serous carcinoma as possible diagnoses. Further elucidation was needed to differentiate between mesothelioma and low-grade serous carcinoma, so we examined the ultrastructure by means of TEM [10]. By TEM, microvilli were identified at the AB-positive apical area of the tumor cells ( Fig.…”

Pericardial Mesothelioma With Thrombovascular Complications (Case From Practice)

“…Ис-следование перикардиальной жидкости чувстви-тельно для цитологической диагностики ПМТП только в 20-24% [24,25], большинство случаев диа-гностики ПМТП (80-90%) базируется на гистоло-гическом исследовании тканей, полученных при перикардэктомии или аутопсии [4,22,26]. Имму-ногистохимический анализ и электронная микро-скопия могут быть необходимы для гистологиче-ской верификации некоторых форм ПМТП [27].…”

The use of electron microscopy for the diagnosis of malignant pleural mesothelioma

“…As for immunohistochemical investigation, there is no a single diagnostic feature, but rather a combination of several ultrastructural features (10). The finding of very long thin apical microvilli and the absence of glycocalyx help to distinguish epithelioid MPM form primary or metastatic lung adenocarcinoma, since the latter display short microvilli that usually have a glycocalyx (9)(10)(11). Perinuclear tonofilament bundles, the presence of basal lamina and long desmosomes are characteristic of adenocarcinoma and not documented in MPM (9)(10)(11).…”

“…The finding of very long thin apical microvilli and the absence of glycocalyx help to distinguish epithelioid MPM form primary or metastatic lung adenocarcinoma, since the latter display short microvilli that usually have a glycocalyx (9)(10)(11). Perinuclear tonofilament bundles, the presence of basal lamina and long desmosomes are characteristic of adenocarcinoma and not documented in MPM (9)(10)(11). Paraffin block and formalin fixation may be satisfactory, since microvilli and tonofilament bundles are enough preserves in formalinfixed samples, but unfortunately this is not the rule.…”