A 42-year-old male presented with intraorbital mass in the kidney. The tumor was resected and the patient relapsed in 2011, 2013 and 2018 after radiation therapy. He died one year after the last treatment with widespread metastases.
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The tumor was composed of sheets of large polygonal cells with pleomorphic vesicular nuclei and prominent nucleoli. The neoplastic cells showed eosinophilic cytoplasm with rhabdoid features. There were also pleomorphic cells, and a minor spindle cell component.
What is the most likely diagnosis of this renal tumor?
A. Epithelioid sarcoma, distal type
B. Proximal type of epithelioid sarcoma
C. Rhabdomyosarcoma
D. Synovial sarcoma
Submitted to the 11th Arkadi M. Rywlin symposium by Franco Fedeli, Malpighi Pathology Academy, Florence, Italy.
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Answer to January/February’s Case of the Month
D. HEY1-NCOA2 fusion
This case demonstrates a mesenchymal chondrosarcoma, a bone or soft tissue lesion with a predilection for adolescents and young adults (1). Characteristically, these malignant tumors show a biphasic morphology: a small round blue cell component and a mature hyaline cartilage component. Mesenchymal chondrosarcomas are most commonly associated with HEY1-NCOA2 fusions. However, these tumors show a degree of genetic heterogeneity and have less frequently shown IRF2BP2-CDX1 fusion. The genetic abnormality t(11;12)(q24;12) - resulting in a EWSR1-FLI1 fusion - is often seen in Ewing sarcoma, another lesion with prominent small round blue cells.
Submitted by Megan C. Smith, Resident in Anatomic and Clinical Pathology, Vanderbilt University Medical Center, Department of Pathology, Microbiology, and Immunology, Nashville, TN, USA.
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References
- PathologyOutlines (2023). Available at: https://bit.ly/3OfBbiy.
