Primary Peritoneal Low-grade Serous Carcinoma in a Patient With Lynch Syndrome: A Case Report

Our plain-English summary of Primary Peritoneal Low-grade Serous Carcinoma in a Patient With Lynch Syndrome: A Case Report, by S. Makiuchi, H. Yoshida, M. Ishikawa, et al (International Journal of Gynecological Pathology, 2020).

The study

• Authors: S. Makiuchi, H. Yoshida, M. Ishikawa, N. Kojima, Y. Kanai, T. Kato
• Journal: International Journal of Gynecological Pathology
• Published: 2020;39(4):327-332
• Type of article: Case report, Review
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Lynch syndrome (LS) is an autosomal dominant disease caused by a germline mutation in DNA mismatch repair genes which increases the risk of several cancers such as endometrial and colorectal cancers. However, there are only a few reports of peritoneal malignancies in patients with LS. Herein, we report the first case of a primary peritoneal low-grade serous carcinoma in a woman with LS and provide a literature review of peritoneal malignancies in patients with LS. The patient was a 72-yr-old gravid 2 para 2 Japanese woman with a germline mutation in MLH1. She had a history of colon cancer and endometrial cancer and was treated with total hysterectomy and bilateral salpingo-oophorectomy 14 yr ago. During the follow-up, peritoneal nodules were detected by abdominal computed tomography which were surgically resected. Pathologic examination revealed a low-grade serous carcinoma with cells positive for BerEP4, MOC31, CEA, and WT-1 and negative for BAP1, PAX8, MLH1, and PMS2, by immunohistochemistry. This case report and literature review show that peritoneal low-grade serous carcinoma can occur in patients with LS and that LS-related cancers usually precede primary peritoneal malignancies. The differential diagnosis for peritoneal nodules in patients with LS should, therefore, include peritoneal serous carcinoma and malignant mesothelioma besides metastasis of LS-related cancers. Considering the ambiguous immunophenotypes, a combination of immunohistologic markers would be useful for an accurate diagnosis of such cases.

In plain English

This was a case report with a short literature review by authors at a hospital in Tokyo, Japan. It described a 72-year-old Japanese woman with Lynch syndrome, an inherited condition caused by a mutation in a DNA repair gene, in her case MLH1. She had earlier had colorectal cancer at age 38 and endometrial cancer at 58. The second was treated by removing her uterus, both ovaries and fallopian tubes. Fourteen years later, scans found small nodules in the lining of the abdomen (peritoneum). Tissue examination led to a final diagnosis of primary peritoneal low-grade serous carcinoma, which the authors called the first such case reported in Lynch syndrome. The tumor shared some staining features with epithelioid peritoneal malignant mesothelioma, including positive calretinin, D2-40 and WT-1 and loss of BAP1. The authors found 5 earlier reported primary peritoneal malignancies in Lynch syndrome patients, 2 of them peritoneal mesotheliomas. The article does not mention asbestos. The authors concluded that several staining markers should be used to reach a correct diagnosis.

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 previously reported primary peritoneal malignancies in patients with Lynch syndrome
• Who was studied: One 72-year-old Japanese woman with Lynch syndrome and a germline MLH1 mutation, reported by authors at the National Cancer Center Hospital and Keio University in Tokyo, Japan
• Exposure: No asbestos exposure is reported. The condition studied was Lynch syndrome (germline MLH1 mutation). The patient had prior colorectal cancer at age 38, and endometrial cancer treated by total hysterectomy and removal of both ovaries and fallopian tubes at age 58.
• Main results:
  • Fourteen years after her hysterectomy, a CT-guided biopsy of a peritoneal nodule showed low-grade serous carcinoma.
  • At surgery, widespread small (miliary) nodules were found in the peritoneum. Part of the peritoneum was removed, and systemic chemotherapy was planned for the remaining tumor.
  • The tumor cells stained positive for calretinin, D2-40, MOC31, BerEP4, WT-1, BRAFV600E, CEA and CA19-9, and negative for PAX8, HNF4-alfa, CDX2, BAP1 and HER2.
  • In the tumor, the mismatch repair proteins PMS2 and MLH1 were lost, while MSH6 and MSH2 were retained.
  • The mitotic count was 0 to 2 per 10 high-power fields, and no necrosis was seen.
  • The final pathologic diagnosis was primary peritoneal low-grade serous carcinoma.
  • Some features of the tumor resembled epithelioid peritoneal malignant mesothelioma: its papillary and solid structure and its positivity for the mesothelial markers calretinin, D2-40 and WT-1. Its loss of BAP1 and PAX8 is uncommon in this cancer type.
  • The authors judged that the loss of mismatch repair proteins was probably associated with the germline MLH1 mutation, and that the tumor was Lynch syndrome-related.
  • Literature review: 5 earlier cases of primary peritoneal malignancy in Lynch syndrome patients had been reported: 2 peritoneal malignant mesotheliomas, 2 high-grade serous carcinomas and 1 moderately differentiated carcinoma.
  • In the reported cases, the authors found it difficult to tell peritoneal malignant mesothelioma apart from primary peritoneal carcinoma.
• The authors' conclusion: The authors concluded that, because this tumor's pathological features resembled peritoneal malignant mesothelioma, several immunohistochemical markers should be used to reach a correct diagnosis and appropriate treatment.
• Limitations the authors state:
  • In the earlier reported cases reviewed, detailed tissue and staining findings, including specific epithelial markers such as BerEP4 and MOC31, were given for only 1 mesothelioma case.

Topics

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

Medical terms in this study, explained in our Lexicon: Carcinoma, Germline Mutation, Colorectal Cancer, Bilateral, Wilms Tumor 1 (WT-1), BAP1, Immunohistochemistry, Differential Diagnosis.

Related studies

• Unusual DNA mismatch repair-deficient tumors in Lynch syndrome: a report of new cases and review of the literature — Y. Karamurzin, Z. Zeng, et al. (2012)
• PAX8 Expression in a Subset of Malignant Peritoneal Mesotheliomas and Benign Mesothelium has Diagnostic Implications in the Differential Diagnosis of Ovarian Serous Carcinoma — D.B. Chapel, A.N. Husain, et al. (2017)
• Malignant mesothelioma in Lynch syndrome: A report of two cases and a review of the literature — A.R. Shih, R.L. Kradin (2019)
• Peritoneal well-differentiated papillary mesothelioma coexisting with endometrial adenocarcinoma mimicking peritoneal carcinomatosis: A case report — Y.Y. Chen, P.C. Li, et al. (2020)
• CD24 is highly useful in differentiating high-grade serous carcinoma from benign and malignant mesothelial cells — B. Davidson (2016)
• Metachronous Uterine Endometrioid Adenocarcinoma and Peritoneal Mesothelioma in Lynch Syndrome: A Case Report — Y. Lu, S. Milchgrub, et al. (2017)

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