-Case Reports-

Cytological Assessment of Desmoplastic Malignant Pleural Mesothelioma in an Autopsy Case

Yoko Kawamoto¹, Shoko Kure^1,2, Hironori Katayama³, Kiyoko Kawahara¹, Kiyoshi Teduka¹, Shinobu Kunugi⁴, Munehiko Onda¹, Norio Motoda^1,2 and Ryuji Ohashi¹

¹Department of Integrated Diagnostic Pathology, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
²Department of Diagnostic Pathology, Nippon Medical School Musashikosugi Hospital, Kanagawa, Japan
³Department of Medical Technology and Sciences, International University of Health and Welfare, Chiba, Japan
⁴Department of Analytic Human Pathology, Nippon Medical School, Tokyo, Japan

Introduction: Desmoplastic malignant pleural mesothelioma (DMPM) is a sarcoma-type mesothelioma, comprising approximately 5% of malignant pleural mesotheliomas. Although effusion cytology is commonly used as the primary diagnostic approach for mesothelioma, it may not be useful for DMPM because of the presence of desmoplasia and bland cellular atypia. We report a case, and previously undescribed cytological features, of DMPM that was diagnosed during autopsy.
Case Presentation: A man in his 60s with a history of occupational asbestos exposure was referred to our hospital with right chest pain. A chest CT scan showed right pleural effusion. Thirteen months later, the patient died of respiratory failure. During autopsy, scrape-imprint smears were prepared and cytology of pleural effusions was performed. The scrape-imprint smear samples showed spindle cells with mild nuclear atypia and grooves with fibrous stroma. Pleural effusion cytology revealed spindle cells with mild nuclear atypia, as well as grooves with loose epithelial connections. Histological examination of the right pleura showed spindle cells proliferating with dense collagen fibers, as seen in the cytological samples, thus indicating a diagnosis of DMPM, which was confirmed by fluorescence in situ hybridization.
Conclusion: Cytological procedures such as pleural effusion cytology and scrape-imprinting cytology may help in diagnosing rare tumors such as DMPM.

J Nippon Med Sch 2022; 89: 616-622

Keywords
fluorescence in situ hybridization, autopsy, cytology, desmoplastic malignant pleural mesothelioma, immunohistochemistry

Correspondence to
Shoko Kure, MD, PhD, Department of Integrated Diagnostic Pathology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan
skure@nms.ac.jp

Received, April 19, 2021
Accepted, September 1, 2021