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The Korean Journal of Pathology 2011;45(Suppl 1): S101-S105.
doi: https://doi.org/10.4132/KoreanJPathol.2011.45.S1.S101
Dedifferentiated Extraskeletal Myxoid Chondrosarcoma of the Masticator Space: A Case Report.
Geunyoung Jung, Kyung Ja Cho, Seung Ho Choi, Mi Jung Kim
1Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. mjkim1103@amc.seoul.kr
2Department of Otorhinolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
We describe a 69-year-old woman who presented with a dedifferentiated extraskeletal myxoid chondrosarcoma arising in the left masticator space. Computed tomography and magnetic resonance imaging revealed a 5 cm sized mass in the left masticator space. Histologically, the tumor consisted of two distinct areas. The less cellular area was a low-grade extraskeletal myxoid chondrosarcoma, composed of strands or cords of uniform spindle cells and abundant myxoid stroma. The more cellular, dedifferentiated area corresponded to a high grade myxofibrosarcoma, consisting of anaplastic tumor cells in myxoid stroma and geographic necrosis. The tumor cells of the former area were positive for S-100 protein, microtubule-associated protein-2 (MAP-2) and class III beta-tubulin, but negative for cytokeratin, smooth muscle actin, and desmin. The tumor cells in the latter, pleomorphic area showed MAP-2 and beta-tubulin immunoreactivity with a high Ki-67 labeling index. Based on its histologic and immunohistochemical features, the tumor was considered a dedifferentiated extraskeletal myxoid chondrosarcoma.
Key Words: Extraskeletal myxoid chondrosarcoma; Cell dedifferentiation; Masticator space