A 67-year-old woman had endometrial polypectomy followed by total hysterectomy and bilateral salpingo-oophorectomy (THBSO) due to a large uterine tumor. The surgical pathology specimen showed a 10 cm lesion involving only the uterus. Histologically, the lesion showed spindle cells with mild to moderate cytological atypia in a myxoid background as shown in the photomicrographs below (areas of necrosis were also noted). Polymerase Chain Reaction (PCR)-Based Next-Generation Sequencing demonstrated a fusion between the BCOR and ZC3H7B genes as schematically illustrated.
The correct answer is...
The correct answer is High-grade endometrial stromal sarcoma.
This a very nice example of a high-grade endometrial stromal sarcoma (HGESS) with ZC3H7B-BCOR fusion. HGESS is a category of ESS typically harboring YWHAE-NUTM2 (FAM22) genetic fusion as a result of t(10;17). However, in 2017 a new subtype of HGESS morphologically mimicking myxoid leiomyosarcoma was described. Histologically, these HGESS demonstrate mainly spindled cells with mild to moderate cytological atypia in an abundant myxoid stroma and brisk mitotic activity (yellow arrows point to mitotic figures). Immunohistochemically, they are positive for CD10 and Cyclin D1 (our particular case was shown to be positive for CD10 and PR, while negative for desmin, ALK-1, SMA and keratin). Molecularly, they harbor ZC3H7B-BCOR gene fusions which are usually revealed by sequencing or fluorescence in-situ hybridization. In terms of behavior, these malignancies have a prognosis in-between low-grade endometrial stromal sarcoma and undifferentiated uterine sarcomas.
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|Simone Barreto Siqueira Parrilha Terra, M.D.
Resident, Molecular Genetic Pathology
|Kevin Halling, M.D., Ph.D.
Consultant, Laboratory Genetics and Genomics
Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science