Microcystic variant malignant mesothelioma presenting as a localized paraspinal mass

Our plain-English summary of Microcystic variant malignant mesothelioma presenting as a localized paraspinal mass, by H.M. Ko, Z.S. Kamil, W.R. Geddie (CytoJournal, 2014).

The study

• Authors: H.M. Ko, Z.S. Kamil, W.R. Geddie
• Journal: CytoJournal
• Published: 2014;11:16
• Type of article: Case report
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

A 58-year-old man presented with productive cough and fever. Computed tomography (CT) scan of the chest showed an upper right paraspinal mass. CT-guided fine-needle aspiration biopsy showed lobules of vacuolated cells against a background of myxoid material. The cells demonstrated moderate to severe nuclear atypia and occasional mitoses. Immunohistochemistry revealed tumor cells to be immunoreactive for calretinin, WT-1, D2-40, cytokeratin (CK) 7, AE1/AE3, high molecular weight keratin, vimentin and epithelial membrane antigen, and negative for thyroid transcription factor-1, Ber-EP4, carcinoembryonic antigen, S100 protein, CK20, and CDX2. The combined morphologic and immunohistochemical findings confirmed the diagnosis of microcystic variant of localized malignant mesothelioma. The subsequent lung resection showed a pleural-based mass in the right upper lobe and confirmed the diagnosis. Awareness of the existence of unusual morphologic variants and localized forms of mesothelioma are necessary to avoid misdiagnosis of fine needle biopsy samples. Recognition of characteristic cytomorphologic features along with optimal use of panel of immunohistochemistry studies is crucial for making a specific diagnosis.

In plain English

This case report, by authors based in Toronto, Canada, described one patient: a 58-year-old man with a productive cough and fever. The article stated that he had no history of asbestos exposure. He was an ex-smoker (40 pack/year) who worked as a screenwriter and photographer. A CT scan showed a 5 cm by 4 cm mass beside the spine in the upper right chest, with no pleural effusion (fluid around the lung). A fine-needle aspiration biopsy showed heavily vacuolated cells against a background of myxoid (mucus-like) material, which at first raised other possible tumors such as chordoma and adenocarcinoma. Immunohistochemical stains supported a mesothelial origin, and a localized malignant mesothelioma of the microcystic (adenomatoid) variant was diagnosed. Removal of the right lung found a 4.8 cm tumor based on the pleura that focally invaded the lung and the soft tissue of the chest wall, which confirmed the diagnosis. The patient remained disease free 29 months after surgery. The authors concluded that awareness of unusual variants and localized forms of mesothelioma is necessary because they can be confused with other 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), describing fine-needle aspiration biopsy findings
• Who was studied: one 58-year-old man with productive cough and fever; ex-smoker (40 pack/year) who worked as a screenwriter and photographer; authors at the University of Toronto and University Health Network, Toronto, Canada
• Exposure: The article reports no history of asbestos exposure; no fiber type is named. The patient was an ex-smoker (40 pack/year).
• Main results:
  • CT showed a 5 cm by 4 cm paraspinal mass in the upper right chest; no pleural effusion was detected
  • The aspirate showed lobules of heavily vacuolated epithelioid cells on a myxoid background, initially suggesting chordoma or adenocarcinoma among the possible diagnoses
  • Tumor cells were strongly positive for calretinin, WT-1, D2-40, cytokeratin 7 and AE1/AE3, and moderately positive for high molecular weight keratin (CK5/6), vimentin and epithelial membrane antigen, which supported a mesothelial origin
  • Stains were negative for thyroid transcription factor-1, Ber-EP4, carcinoembryonic antigen, S100 protein, CK20 and CDX-2, which excluded adenocarcinoma and chordoma
  • A diagnosis of localized malignant mesothelioma, microcystic (adenomatoid) variant, was made
  • Right pneumonectomy found a localized, pleura-based 4.8 cm tumor next to the right upper lobe. It involved the parietal and visceral pleura and focally invaded the lung and the chest wall soft tissue.
  • The patient remained disease free 29 months after pneumonectomy
• The authors' conclusion: The authors concluded that malignant mesothelioma, including the microcystic variant, can present as a localized mass. They said awareness of unusual variants and localized forms is necessary because these can be confused with other tumors, and that a broad differential diagnosis and optimal use of immunohistochemistry are crucial.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Fine-Needle Aspiration, Nuclear Atypia, Immunohistochemistry, Calretinin, Wilms Tumor 1 (WT-1), Podoplanin (D2-40), Epithelial Membrane Antigen (EMA).

Related studies

• Microcystic variant of localized malignant mesothelioma accompanying an adenomatoid tumor-like lesion — H. Umezu, K. Kuwata, et al. (2002)
• Localized biphasic malignant mesothelioma presenting as a giant pelvic wall mass: a rare case report and literature review — Y. Liu, J. Wu, et al. (2020)
• Localized malignant peritoneal mesothelioma presenting hepatohilar giant mass — O. Kinoshita (2022)
• Localized malignant pleural mesothelioma showing a thoracic mass and metastasizing to the stomach — H. Hayashi, K. Notohara, et al. (2010)
• Impact of body mass index on the detection of radiographic localized pleural thickening — T.C. Larson, A. Franzblau, et al. (2014)
• Diffuse epithelial pleural mesothelioma presenting as a solitary lung mass — M.H. Gotfried, S.F. Quan, et al. (1983)

Browse more research in CytoJournal, or return to medical research.