Extraskeletal mesenchymal chondrosarcoma mimicking a thrombosed venous aneurysm with femoral vein involvement: A case report. (28th October 2021)

• Record Type: Journal Article
• Authors: Muldoon, J; Warmke, L
• Is Part Of: American journal of clinical pathology. Volume 156(2021)Supplement 1
• Page Start: S25
• Page End: S25
• Publication Date: 2021-10-28
• Subjects: Diagnosis, Laboratory -- Periodicals; Pathology -- Periodicals; 616.07
• DOI: 10.1093/ajcp/aqab191.047
• Languages: English
• ISSNs: 0002-9173

Abstract

Abstract: Introduction/Objective: Mesenchymal chondrosarcoma is a high-grade primitive mesenchymal tumor, which accounts for <5% of all chondrosarcomas and commonly affects young adults (peak incidence in second to third decade of life). The tumor has a widespread anatomic distribution, frequently involving the craniofacial bones as well as extraskeletal sites. The clinical presentation of an inguinal mass mimicking a thrombosed venous aneurysm is unusual and represents a potential diagnostic pitfall. Methods/Case Report: A 42-year-old female with hypertension and obesity initially presented with a two-week history of left lower leg swelling. Venous doppler revealed presumed venous thrombosis, and she was prescribed apixaban while no history of coagulopathy, immobility, or recent surgery was noted. Two months later, she had residual swelling. Follow-up CT scan favored a large, peripherally thrombosed venous aneurysm arising from the left common femoral vein, while MRI showed a lobulated, inguinal soft tissue mass abutting the vein. Biopsy of the mass demonstrated a spindle cell mesenchymal neoplasm; subsequent resection revealed a pink-to-tan, well-circumscribed, and encapsulated mass (5.2 cm) with focal left common femoral vein invasion. Microscopically, the lesion demonstrated poorly-differentiated, oval-to-spindle cells with prominent staghorn vasculature interspersed were focal areas of well-differentiated hyaline cartilage. Immunohistochemical stains showed that the lesional cells were negative for cytokeratin cocktail, EMA, SMA, desmin, S100 protein, SOX10, STAT6, MUC4, MDM2, and ER. Next-generation sequencing (NGS) revealed a HEY1-NCOA2 gene fusion, confirming the diagnosis of extraskeletal mesenchymal chondrosarcoma. Results (if a Case Study enter NA): N/A Conclusion: Extraskeletal mesenchymal chondrosarcoma can rarely present as an inguinal soft tissue mass with vascular invasion, mimicking a thrombosed venous aneurysm. Molecular confirmation of HEY1-NCOA2 gene fusion can help confirm the diagnosis in unusual clinical presentations.