Adenomatoid mesothelioma arising from the diaphragm: a case report and review of the literature

Abstract

Background Adenomatoid mesothelioma is a rare subtype of malignant mesothelioma that can be confused with adenomatoid tumors, which are classified as benign. The clinical features and optimal management of adenomatoid mesothelioma have not been elucidated in the literature. In this report, we present an extremely rare case of adenomatoid mesothelioma that developed on the peritoneal surface of the diaphragm as well as a literature review of adenomatoid mesothelioma in the abdominal cavity. Case presentation The patient was a 61-year-old Japanese woman who had undergone resection of a malignant peripheral nerve sheath tumor of the hand 18 years prior. She was diagnosed with clinical stage I lung adenocarcinoma on follow-up chest radiography. Simultaneously, a 20-mm enhancing nodule with slow growth on the right diaphragm was detected on contrast-enhanced computed tomography. She presented no specific clinical symptoms. At this point, the lesion was suspected to be a hypervascular tumor of borderline malignancy, such as a solitary fibrous tumor. After a left upper lobectomy for lung adenocarcinoma, she was referred to our department, and laparoscopic tumor resection was performed. Adenomatoid tumors were also considered based on the histopathological and immunohistochemical analyses, but we made the final diagnosis of adenomatoid mesothelioma using the results of the genetic profile. The patient remains alive, with no recurrence noted 6 months after surgery. Conclusion We encountered a valuable case of adenomatoid mesothelioma of peritoneal origin. There are some previously reported cases of adenomatoid mesothelioma and adenomatoid tumors that may need to be recategorized according to the current classification. It is important to accumulate and share new findings to clarify the clinicopathological characteristics and genetic status of adenomatoid mesothelioma.

NR4A3 fusions characterize a distinctive peritoneal mesothelial neoplasm of uncertain biological potential with pure adenomatoid/microcystic morphology

“…Adenomatoid features are much less common in peritoneal mesothelioma 3–5 . A review of the literature reveals seven cases of peritoneal mesothelial neoplasms reported as adenomatoid mesothelioma, microcystic mesothelioma, or multifocal mesothelial adenomatoid tumors 55–61 . However, some of these cases were associated with conventional mesothelioma component, 55 and accompanying genetic analysis was not described.…”

“…[3][4][5] A review of the literature reveals seven cases of peritoneal mesothelial neoplasms reported as adenomatoid mesothelioma, microcystic mesothelioma, or multifocal mesothelial adenomatoid tumors. [55][56][57][58][59][60][61] However, some of these cases were associated with conventional mesothelioma component, 55 and accompanying genetic analysis was not described. The tumor reported by Mori et al as adenomatoid peritoneal mesothelioma in a 64-year-old woman was strikingly adenomatoid, but the lung metastases resected 4 years later were more akin to conventional solid epithelioid mesothelioma.…”