Usefulness of electron microscopy in the diagnosis of wild-type transthyretin cardiac amyloidosis. Issue 4 (April 2021)

• Record Type: Journal Article
• Authors: Sunayama, Isamu; Yoshimura, Takahiro; Sonoura, Takuryu; Nakamura, Yuka; Morishita, Yu; Sekihara, Takayuki; Ishimi, Masashi; Yamato, Masashi; Hoshida, Yoshihiko; Yasuoka, Yoshinori
• Is Part Of: Journal of cardiology cases. Volume 23:Issue 4(2021)
• Page Start: 166
• Page End: 169
• Publication Date: 2021-04
• Subjects: Transthyretin cardiac amyloidosis -- Heart failure -- Diagnostic strategies -- Electron microscopy -- Preserved ejection fraction; Cardiology -- Periodicals; Cardiovascular Diseases -- Case Reports; Cardiovascular Diseases -- Periodicals; Cardiology -- Case Reports; Cardiology -- Periodicals; Cardiology; Electronic journals; Periodicals; 616.12
• DOI: 10.1016/j.jccase.2020.11.023
• Languages: English
• ISSNs: 1878-5409

Abstract

Abstract: Wild-type transthyretin cardiac amyloidosis (ATTRwt) has been recognized as an important cause of heart failure with preserved ejection fraction; thus, its accurate diagnosis is crucial. Herein, we describe the case of a 76-year-old man who presented with dyspnea and palpitation. On observing the laboratory evaluations and clinical course, we suspected cardiac amyloidosis. However, optical microscopic analysis by Congo-red and direct fast scarlet staining revealed no amyloid deposits in the biopsy samples. Therefore, a more thorough investigation was pursued by examining the myocardial tissue under electron microscopy. We could recognize amyloid deposits between the myocardial fibers using electron microscopy. We submitted all the pathological specimens to a specialized facility for genetic testing to ensure the accurate diagnosis of the amyloidosis disease type. As a result, a biopsy sample from the minor salivary gland was stained with the Congo red stain. Anti-transthyretin antibody detected using immunohistochemical analysis of amyloidosis supported the presence of transthyretin form of amyloid proteins. Genetic testing revealed the absence of TTR gene mutations. The final diagnosis was ATTRwt. We believe that this case suggests the usefulness of electron microscopy in the diagnosis of ATTRwt and other related disorders. Further study is warranted to validate our findings.