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Lenz J, Klubíčková N, Ptáková N, Hájková V, Grossmann P, Šteiner P, Kinkor Z, Švajdler M, Michal M, Konečná P, Macháčová D, Hurník P, Tichý M, Tichý F, Kyllar M, Fiala L, Kavka M, Michal M. Extraskeletal myxoid chondrosarcoma: A study of 17 cases focusing on the diagnostic utility of INSM1 expression and presenting rare morphological variants associated with non-EWSR1::NR4A3 fusions. Hum Pathol 2022; 134:19-29. [PMID: 36563884 DOI: 10.1016/j.humpath.2022.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 11/18/2022] [Accepted: 12/15/2022] [Indexed: 12/25/2022]
Abstract
Extraskeletal myxoid chondrosarcoma (EMC) is a rare sarcoma of uncertain lineage. Insulinoma-associated protein 1 (INSM1) has recently been described as a highly specific and sensitive immunohistochemical marker for EMC. The goal of this study was to evaluate the diagnostic significance of INSM1 immunohistochemistry in EMC. Furthermore, correlations between molecular and morphological findings were performed. Sixteen of 17 EMC cases were stained with the INSM1 antibody. Tumors with at least 5% INSM1-positive cells and any staining intensity were considered positive. Molecular testing was successfully performed in 12/17 cases. The immunohistochemical analysis detected 13 INSM1-positive (81%) and 3 INSM1-negative tumors (19%). The extent of the staining was classified as 1+ in 7 cases (44%), 2+ in 2 cases (13%), 3+ in 2 cases (13%) and 4+ in 2 cases (13%). Intensity of immunostaining was weak in 5 cases (31%), moderate in 2 cases (13%) and strong in 6 cases (38%). Molecular assays revealed 8 EWSR1::NR4A3 positive tumors (67%), 2 TAF15::NR4A3 positive tumors (17%), 1 TCF12::NR4A3 positive tumor (8%) and 1 NR4A3 positive tumor (8%) in which no other gene alteration was identified. Two of them, namely TCF12 positive and one TAF15 positive tumors, were highly cellular and partially associated with pseudopapillary architecture. Our study found that moderate/strong expression of INSM1 in more than 25% of tumor cells was present in only 31% of cases. Thus, the diagnostic utility of INSM1 is rather low. Two morphologically unique cases of non-EWSR1 rearranged EMC with an extremely rare pseudopapillary growth pattern are also reported.
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Affiliation(s)
- Jiří Lenz
- Department of Pathology, Znojmo Hospital, MUDr. Jana Janského 2675/11, 669 02 Znojmo, Czech Republic; Cytohisto S.r.o., Bří. Mrštíků 3065, 690 02 Břeclav, Czech Republic; Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Palackého Tř. 1946/1, 612 42 Brno, Czech Republic.
| | - Natálie Klubíčková
- Department of Pathology, Faculty of Medicine in Pilsen, Charles University, Husova 3, 301 00 Plzeň, Czech Republic; Bioptical Laboratory, Ltd., Mikulášské Nám. 4, 326 00 Pilsen, Czech Republic.
| | - Nikola Ptáková
- Bioptical Laboratory, Ltd., Mikulášské Nám. 4, 326 00 Pilsen, Czech Republic.
| | - Veronika Hájková
- Bioptical Laboratory, Ltd., Mikulášské Nám. 4, 326 00 Pilsen, Czech Republic.
| | - Petr Grossmann
- Bioptical Laboratory, Ltd., Mikulášské Nám. 4, 326 00 Pilsen, Czech Republic.
| | - Petr Šteiner
- Bioptical Laboratory, Ltd., Mikulášské Nám. 4, 326 00 Pilsen, Czech Republic.
| | - Zdeněk Kinkor
- Department of Pathology, Faculty of Medicine in Pilsen, Charles University, Husova 3, 301 00 Plzeň, Czech Republic; Bioptical Laboratory, Ltd., Mikulášské Nám. 4, 326 00 Pilsen, Czech Republic.
| | - Marián Švajdler
- Department of Pathology, Faculty of Medicine in Pilsen, Charles University, Husova 3, 301 00 Plzeň, Czech Republic; Bioptical Laboratory, Ltd., Mikulášské Nám. 4, 326 00 Pilsen, Czech Republic.
| | - Michal Michal
- Department of Pathology, Faculty of Medicine in Pilsen, Charles University, Husova 3, 301 00 Plzeň, Czech Republic; Bioptical Laboratory, Ltd., Mikulášské Nám. 4, 326 00 Pilsen, Czech Republic.
| | - Petra Konečná
- Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Palackého Tř. 1946/1, 612 42 Brno, Czech Republic.
| | - Dominika Macháčová
- Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Palackého Tř. 1946/1, 612 42 Brno, Czech Republic.
| | - Pavel Hurník
- Institute of Molecular and Clinical Pathology and Medical Genetics, Faculty of Medicine, University of Ostrava, Syllabova 19, 703 00 Ostrava, Czech Republic.
| | - Michal Tichý
- Department of Pathology, Masaryk Memorial Cancer Institute, Žlutý Kopec 543/7, 602 00, Brno, Czech Republic.
| | - František Tichý
- Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Palackého Tř. 1946/1, 612 42 Brno, Czech Republic.
| | - Michal Kyllar
- Institute of Morphology, Department of Pathobiology, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria.
| | - Luděk Fiala
- Cytohisto S.r.o., Bří. Mrštíků 3065, 690 02 Břeclav, Czech Republic; Charles University Prague, First Faculty of Medicine, Kateřinská 1660/32, 121 08 Prague, Czech Republic.
| | - Miroslav Kavka
- Department of Surgery, Znojmo Hospital, MUDr. Jana Janského 2675/11, 669 02 Znojmo, Czech Republic.
| | - Michael Michal
- Department of Pathology, Faculty of Medicine in Pilsen, Charles University, Husova 3, 301 00 Plzeň, Czech Republic; Bioptical Laboratory, Ltd., Mikulášské Nám. 4, 326 00 Pilsen, Czech Republic.
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