Desmoplastic small round cell tumor with sphere-like clusters mimicking adenocarcinoma

Our plain-English summary of Desmoplastic small round cell tumor with sphere-like clusters mimicking adenocarcinoma, by Y. Hattori, A. Yoshida, N. Sasaki, et al (Diagnostic Cytopathology, 2015).

The study

• Authors: Y. Hattori, A. Yoshida, N. Sasaki, Y. Shibuki, K. Tamura, K. Tsuta
• Journal: Diagnostic Cytopathology
• Published: 2015;43(3):214-7
• Type of article: Case report
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Desmoplastic small round cell tumor (DSRCT) is a rare and aggressive neoplasm that predominantly affects young men. DSRCT often presents as multiple nodules on the serosal surface and is histologically categorized as a small round cell tumor. However, the cytological spectrum of DSRCT is not fully understood because of its rarity. Here, we report an unusual case of DSRCT that showed spheres of cells without stromal cores in pleural fluid cytology material, a finding that is typically associated with metastatic adenocarcinoma and mesothelioma. The specimen from a simultaneous needle biopsy showed the classic histology of DSRCT, comprising nests of small round cells set in desmoplasia. The diagnosis of DSRCT was further supported by immunohistochemical coexpression of cytokeratin and desmin, as well as Ewing sarcoma breakpoint region 1 gene rearrangement, which was determined by fluorescence in situ hybridization. The unusual cytological finding in this case illustrates a potential pitfall of the cytological diagnosis of pleural fluid or ascites. DSRCT should not be excluded from the differential diagnosis when sphere-like round cell clusters are observed in pleural or abdominal effusion, particularly in young male patients.

© 2014 Wiley Periodicals, Inc.

In plain English

This was a case report of one patient with desmoplastic small round cell tumor (DSRCT), a rare cancer. It did not study asbestos. Mesothelioma was not investigated; it was mentioned as a look-alike under the microscope and as a possible diagnosis in older patients with multiple pleural or peritoneal masses. A 30-year-old man had weight loss and night sweats. A CT scan showed right pleural and abdominal fluid and multiple tumor masses, but no obvious primary site. In fluid from around the lung, tumor cells formed hollow, ball-like clusters without a central core. The authors said this pattern is usually linked with metastatic adenocarcinoma and mesothelioma. A needle biopsy of the pleural mass showed small round tumor cells in nests. The tumor was positive for cytokeratin and desmin, and a genetic test found an EWSR1 gene rearrangement, supporting DSRCT. The patient died 17 months after his weight loss began. The authors concluded that rare DSRCT cases can show such clusters, a pitfall to remember in young patients. As a limitation, they noted no excisional biopsy or autopsy.

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)
• Who was studied: One 30-year-old man with weight loss and night sweats; the article does not say where or when he was seen
• Main results:
  • In this patient, CT showed disseminated malignant disease but no obvious primary site
  • In the patient's pleural fluid, tumor cells formed three-dimensional clusters, most less than 0.1 mm across. The clusters had no stromal cores and had a single layer of cells around a hollow center.
  • The needle biopsy of the pleural mass showed small round tumor cells in discrete nests within a desmoplastic stroma
  • Immunostaining was positive for pan cytokeratin AE1/AE3, desmin and vimentin
  • Immunostaining was negative for WT1 (N-terminus), thyroid transcription factor-1 and cytokeratin 5/6
  • FISH on the pleural fluid cell block showed EWSR1 gene rearrangement
  • The patient died of multiorgan failure 17 months after first experiencing weight loss; no autopsy was performed
• The authors' conclusion: The authors concluded that the case showed previously unreported proliferation sphere-like clusters in DSRCT. Such clusters are classically associated with carcinomas or mesotheliomas, but rare DSRCT cases may show them too. The authors called this a diagnostic pitfall to remember in young patients with effusion and abdominal masses.
• Limitations the authors state:
  • No excisional biopsy or autopsy was performed for precise histologic correlation

Topics

Medical terms in this study, explained in our Lexicon: Desmoplastic Small Round Cell Tumor, Adenocarcinoma, Neoplasm, Serosal Surface, Fluid Cytology, Mesothelioma, Needle Biopsy, Histology.

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• Small cell carcinoma presenting with massive pleural spread mimicking malignant pleural mesothelioma — T. Takeda, M. Saitoh, et al. (2014)
• Third-space fluid distribution of pemetrexed in non-small cell lung cancer patients — P.H. Honoré, S.J. Joensen, et al. (2014)
• Claudin-4 immunohistochemistry is highly effective in distinguishing adenocarcinoma from malignant mesothelioma in effusion cytology — V.Y. Jo, E.S. Cibas, et al. (2014)
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