Non-mesenchymal Mimics of Sarcoma

Our plain-English summary of Non-mesenchymal Mimics of Sarcoma, by L.A. Doyle (Surgical Pathology Clinics, 2015).

The study

• Author: L.A. Doyle
• Journal: Surgical Pathology Clinics
• Published: 2015;8(3):493-513
• Type of article: Review
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A variety of different non-mesenchymal neoplasms may mimic sarcoma, in particular sarcomatoid carcinoma and melanoma, but also mesothelioma and rarely some lymphomas. This article reviews the key clinical and histologic features of such neoplasms in different settings, along with the use of ancillary studies to help identify the tumor types most frequently misdiagnosed as sarcoma.

Copyright © 2015 Elsevier Inc. All rights reserved.

In plain English

This article was a narrative review in a pathology journal about tumors that are not sarcomas but can look like sarcomas under the microscope. It did not study a group of patients and did not mention asbestos. The review covered melanoma, sarcomatoid carcinoma, some lymphomas and related blood-cell tumors, and malignant mesothelioma, along with the laboratory stains and genetic tests that help tell them apart. On mesothelioma, the review stated that it can mimic several sarcoma types in the pleura and, less commonly, the abdominal cavity, mostly when it has a spindled or sarcomatoid appearance. Citing earlier studies, it stated that sarcomatoid mesothelioma usually stains for cytokeratins but usually not for CK5/6 or WT1. It also stated that calretinin is found in 70% of sarcomatoid mesotheliomas but also in 60% of sarcomatoid carcinomas and up to 20% of sarcomas, so a panel of stains is usually needed. It described a rare deciduoid variant of mesothelioma as having an aggressive clinical course. The author concluded that knowing this overlap is essential to avoid erroneous diagnoses.

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: Narrative review of diagnostic pathology (no original patient data), illustrated with example tissue images
• Who was studied: No study population. The article reviewed published literature on tumors that mimic sarcoma and used individual example cases only as illustrations.
• Exposure: No exposure was studied. Asbestos is not mentioned in the article.
• Main results:
  • The review stated that malignant mesothelioma, in the pleura and less commonly the abdominal cavity, may mimic several sarcoma types, most often when it has spindled or sarcomatoid morphology.
  • The review stated that most primary peritoneal mesotheliomas are epithelioid. The main tumor they must be distinguished from is papillary serous carcinoma of gynecologic origin or other carcinomas.
  • In the abdominal cavity, sarcomatoid mesothelioma was described as possibly mimicking dedifferentiated liposarcoma, inflammatory myofibroblastic tumor, sclerosing mesenteritis, or sarcomatoid carcinoma.
  • Citing an earlier study, the review stated that sarcomatoid mesotheliomas usually express cytokeratins but are usually negative for the more specific mesothelioma markers CK5/6 and WT1.
  • Citing earlier studies, the review stated that calretinin is expressed in 70% of sarcomatoid mesotheliomas.
  • Citing earlier studies, the review stated that calretinin is also seen in 60% of sarcomatoid carcinomas and up to 20% of sarcomas, so a panel of stains is usually needed.
  • The rare deciduoid variant of mesothelioma, arising in the pleural or peritoneal cavities, was described as mimicking histiocytic neoplasms, germ cell tumors or carcinoma, and as having an aggressive clinical course.
  • Outside mesothelioma, the review stated that sarcomatoid carcinoma is most often associated with breast, renal cell and squamous cell carcinomas.
  • The review stated that lymphoblastic lymphoma can mimic Ewing sarcoma, partly because up to 80% of cases show diffuse membranous CD99 expression.
• The authors' conclusion: The author concluded that knowledge of the overlap in microscopic appearance between non-mesenchymal tumors (melanoma, sarcomatoid carcinoma, mesothelioma and some blood-cell tumors) and sarcomas is essential in all areas of pathology to avoid erroneous diagnoses, which may have significant clinical implications.

Topics

Medical terms in this study, explained in our Lexicon: Sarcoma, Neoplasm, Sarcomatoid, Carcinoma, Mesothelioma.

Related studies

• Epithelioid sarcoma. A clinical and pathologic study of nine cases — H. Santiago, L.K. Feinerman, et al. (1972)
• Metastatic proximal epithelioid sarcoma in pleural effusion: cytopathologic findings and differential diagnosis — H. Guan, F. Haque, et al. (2013)
• Expression of E-cadherin in bone and soft tissue sarcomas: a possible role in epithelial differentiation — H. Sato, T. Hasegawa, et al. (1999)
• A case of pleural epithelioid sarcoma of proximal type presenting as malignant pleural mesothelioma — G.A. Madsen, T.R. Rasmussen, et al. (2013)
• NY-ESO-1 expression in synovial sarcoma and other mesenchymal tumors: significance for NY-ESO-1-based targeted therapy and differential diagnosis — J.P. Lai, P.F. Robbins, et al. (2012)
• Sarcomas in organ allograft recipients — I. Penn (1995)

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