Extraskeletal myxoid chondrosarcoma of the thigh with a t(9;17) translocation

Abstract

Extraskeletal myxoid chondrosarcomas (EMC) are relatively rare. We report a case of EMC of the thigh. A 41-year-old man presented with a tumor history of more than 4 months. Following open biopsy, wide resection of the tumor was performed. Histopathologically, the tumor had a multinodular architecture consisting of myxomatous areas demarcated by fibrous septa. Proliferation of uniform, round tumor cells with oval nuclei was observed. Well-formed hyaline cartilage and rhabdoid-like cells were not visible. Immunohistochemically, the tumor cells were positive for vimentin and S-100. The composite karyotype was 46,XY,t(9;17)(q22;q11),t(9;21)(q21;p13), and the diagnosis of EMC was made. No recurrence of the mass or metastasis was observed during a follow-up period of 4 years and 7 months. Only 50 cytogenetic cases of EMC, including our case, have been reported in the English literature thus far. Clinical presentation, radiological features and histopathological and cytogenetic findings are described, and the relevant literature is reviewed.

Figure 1

MRI findings. (A) T1-weighted axial imaging; (B) T2-weighted axial imaging. MRI shows an intramuscular, low signal intensity mass located in the rectus femoris and tensor fascia latae (arrow). (C) T1-weighted frontal MRI image after contrast enhancement shows a multinodular, heterogeneous, high signal intensity mass (arrow).

Figure 1

MRI findings. (A) T1-weighted axial imaging; (B) T2-weighted axial imaging. MRI shows an intramuscular, low signal intensity mass located in the rectus femoris and tensor fascia latae (arrow). (C) T1-weighted frontal MRI image after contrast enhancement shows a multinodular, heterogeneous, high signal intensity mass (arrow).

Figure 2

G-banded karyotype. The translocation t(9;17)(q22;q12) was identified (large arrows). The translocation t(9;21)(q21;p13) was also observed in this case (small arrows).

Figure 3

Gross appearance of surgical specimens. The tumor was encased by a thin capsule and divided into multiple gelatinous nodules by fibrous tissue. The hemorrhagic area is shown (asterisk).

Figure 4

Histological appearance of surgical specimen. (A) Lace-like appearance with an abundant myxoid matrix is shown (hematoxylin and eosin; scale bar, 200 μm). (B) Diffuse proliferation of small, uniform, round cells with hyperchromatic nuclei is observed. Mitoses are rare (hematoxylin and eosin; scale bar, 50 μm).

Figure 4

Histological appearance of surgical specimen. (A) Lace-like appearance with an abundant myxoid matrix is shown (hematoxylin and eosin; scale bar, 200 μm). (B) Diffuse proliferation of small, uniform, round cells with hyperchromatic nuclei is observed. Mitoses are rare (hematoxylin and eosin; scale bar, 50 μm).