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

Our plain-English summary of Adenomatoid mesothelioma arising from the diaphragm: a case report and review of the literature, by K. Kawabe, H. Sato, A. Kitano, et al (Journal of Medical Case Reports, 2022).

The study

• Authors: K. Kawabe, H. Sato, A. Kitano, R. Yoshida, K. Yasui, Y. Umeda, K. Yoshida, T. Fuji, K. Kumano, K. Takagi, M. Kagoura, T. Yagi, T. Fujiwara
• Journal: Journal of Medical Case Reports
• Published: 2022;16(1):228
• Type of article: Case report, Review
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

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.

© 2022. The Author(s).

In plain English

This article was a case report with a literature review. The authors described a 61-year-old Japanese woman who had a malignant peripheral nerve sheath tumor removed from her hand at age 43. She was a current smoker and had no history of asbestos exposure. While she was being diagnosed with stage I lung adenocarcinoma, a scan found a 20-mm, slowly growing nodule on the right diaphragm. She had no symptoms. After her lung surgery, surgeons removed the nodule laparoscopically. It grew from the abdominal (peritoneal) surface of the diaphragm and pressed on the liver without apparent invasion. Tissue staining and genetic tests (no TRAF7 hot-spot mutations, no homozygous 9p21 or hemizygous NF2 deletion) led to a diagnosis of localized adenomatoid mesothelioma, a rare subtype of malignant mesothelioma. No recurrence was seen 6 months after surgery. In a PubMed search, the authors found six abdominal cases including this one (one man, five women). None had a history of asbestos exposure, and one had recurred. The authors concluded that sharing such cases may lead to better characterization of the disease.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case report of one patient, with a literature review of adenomatoid mesothelioma in the abdominal cavity
• Who was studied: One 61-year-old Japanese woman, treated at Okayama University Hospital, Japan. At age 43 she had had a malignant peripheral nerve sheath tumor of the hand removed. She was later diagnosed with clinical stage I lung adenocarcinoma.
• Exposure: No asbestos exposure was reported. The patient was a current smoker with no history of asbestos exposure.
• Main results:
  • Contrast-enhanced CT found a 20-mm enhancing, slowly growing nodule on the patient's right diaphragm.
  • At laparoscopic surgery, the tumor was compressing liver segment 8 but had not apparently invaded it.
  • The removed tumor measured 28 by 20 by 11 mm.
  • Tumor cells were positive for the mesothelial markers CK5/6 and calretinin and negative for CEA and TTF-1. The authors used this pattern to rule out spread of the lung adenocarcinoma.
  • Staining was negative for CD34 and STAT6, which ruled out a solitary fibrous tumor (the first suspected diagnosis).
  • Sanger sequencing of TRAF7 hot-spot sites (codons 519, 521, 538, 561 and 577) detected no mutations. TRAF7 mutations are reported to define adenomatoid tumors, the benign look-alike.
  • FISH testing showed no homozygous deletion of 9p21 and no hemizygous deletion of NF2.
  • The patient was diagnosed with localized adenomatoid mesothelioma.
  • No recurrence was seen 6 months after surgery.
  • The PubMed literature search found six reported cases of adenomatoid mesothelioma in the abdominal cavity, including this one.
  • Of these six cases, one was a man and five were women, and none had a history of asbestos exposure.
  • Recurrence was not observed in five of the six reported patients. One case (reported by Mori et al.) recurred after curative resection.
  • Some earlier reports described adenomatoid mesothelioma as benign, and some described adenomatoid tumors invading nearby organs. The authors stated these patients may need to be recategorized under the current WHO classification.
• The authors' conclusion: The authors concluded that they had encountered a case of adenomatoid mesothelioma of peritoneal origin, and that accumulating and sharing such cases may lead to better characterization of the disease.
• Limitations the authors state:
  • The authors noted that the best follow-up strategy for this patient has not been well established.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Adenomatoid Tumor, Mesothelioma, Diaphragm, Lung Adenocarcinoma, Solitary Fibrous Tumor.

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