Localized biphasic malignant peritoneal mesothelioma presenting as a rectal tumor

Our plain-English summary of Localized biphasic malignant peritoneal mesothelioma presenting as a rectal tumor, by K. Saisho, S. Fujiwara, K. Anami, et al (Clinical Journal of Gastroenterology, 2020).

The study

• Authors: K. Saisho, S. Fujiwara, K. Anami, R. Matsumoto, T. Kusaba, T. Daa, K. Nabeshima, Y. Akagi
• Journal: Clinical Journal of Gastroenterology
• Published: 2020;13(3):308-315
• Type of article: Case report
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

An 84-year-old male presented with bloody stool. On digital rectal examination, a large and firm tumor was palpated in the anterior wall of the rectum at 2 cm from the anal verge. The colonoscopy revealed an ulcerated mass with smooth margins in the anterior wall of the rectum. Enhanced computed tomography showed a huge tumor in the pelvis, invading rectum, urinary bladder and the prostate, with signs of splenic and peritoneal metastases. Findings from an endoscopic biopsy and endoscopic ultrasound-guided fine needle aspiration suggested spindle cell carcinoma. We tentatively diagnosed as spindle cell carcinoma of the rectum and administered panitumumab as palliative chemotherapy. He eventually died at 4 months after the first visit to our institution. The autopsy findings resulted in the confirmed diagnosis as biphasic malignant peritoneal mesothelioma. There are only four previous reports on malignant peritoneal mesothelioma presenting as a colorectal tumor. Although rare, malignant peritoneal mesothelioma should be considered in differential diagnosis of colorectal tumors.

In plain English

This case report from Japan described an 84-year-old man who had two weeks of bloody stool and, according to the report, no occupational history of asbestos exposure. A CT scan showed an 8 cm tumor in the pelvis invading the rectum, bladder and prostate, with spread to the spleen and peritoneum. Biopsies suggested spindle cell carcinoma, so the doctors made a tentative diagnosis of spindle cell carcinoma of the rectum. He received only one course of panitumumab as palliative treatment because of fatigue and fever. The tumor grew to 11 cm over 3 months, and he died 4 months after his first visit. An autopsy that included tissue stains and a gene test confirmed biphasic malignant peritoneal mesothelioma, a cancer of the abdominal lining with two types of cells. When the earlier biopsy samples were restained after the autopsy, they were positive for the mesothelioma marker D2-40. The authors found five reported cases, including this one, of this cancer presenting as a colorectal tumor. They concluded that, although rare, it should be considered when diagnosing colorectal tumors.

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 (single patient, diagnosis confirmed at autopsy), with a short comparison to previously published cases
• Who was studied: one 84-year-old man treated at a medical center in Oita, Japan; dates of care not given
• Exposure: the report states the patient had no occupational history of asbestos exposure; no fiber type or dose is given
• Main results:
  • At the first visit, CT showed a pelvic mass 8 cm in largest diameter invading the rectum and urinary bladder (and, per the text, the prostate), with metastases in the spleen and peritoneum
  • Biopsy and fine needle aspiration findings led to a tentative diagnosis of spindle cell carcinoma of the rectum
  • The patient received only one course of panitumumab because of general fatigue and fever
  • The tumor grew to 11 cm in maximum diameter over 3 months
  • The patient died 4 months after his first visit
  • At autopsy, the primary tumor had an epithelial component and a sarcomatous component, and the tumor cells showed homozygous deletion of the CDKN2A/p16 gene; biphasic malignant peritoneal mesothelioma was confirmed
  • After the autopsy, additional staining of the earlier endoscopic biopsy specimens was positive for D2-40, a mesothelioma marker
  • The authors identified five reported cases of malignant peritoneal mesothelioma presenting as a colorectal tumor, including this one
• The authors' conclusion: The authors concluded that, although rare, malignant peritoneal mesothelioma should be considered as a possible diagnosis for colorectal tumors
• Limitations the authors state:
  • The authors noted that the diagnosis was not made before treatment, and that a laparoscopic biopsy of the omental or mesenteric nodules might have allowed it

Topics

Medical terms in this study, explained in our Lexicon: Biphasic Mesothelioma, Peritoneal Mesothelioma, Biopsy, Ultrasound, Spindle Cell, Carcinoma, Palliative Care, Chemotherapy.

Related studies

• Simultaneous occurrence of a rectal carcinoma and a diffuse well differentiated papillary mesothelioma of the peritoneum — G.R. Jatzko, J. Jester (1997)
• Benign localized fibrous tumor of the pleura: report of 25 new cases — S. Enon, D. Kilic, et al. (2012)
• Occupational Asbestos Exposure and Incidence of Colon and Rectal Cancers in French Men: The Asbestos-Related Diseases Cohort (ARDCo-Nut) — C. Paris, I. Thaon, et al. (2017)
• American Cancer Society plans for a long-range study of colonic and rectal cancer — E.C. Hammond (1970)
• Sarcomatoid malignant peritoneal mesothelioma presenting as a localized mesenteric tumor with no previous asbestos exposure — Y.A. Notue, U.I. Mbessoh, et al. (2020)
• Localized malignant pleural mesothelioma — T. Nakano, R. Hamanaka, et al. (2012)

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