Case 88

A 73-year-old female with a uterine mass concerning for leiomyosarcoma.

1. What's the molecular finding of this lesion?

   A: ALK-FN1

   B: JAZF1-PHF1

   C: BCOR ITD

   D: YWHAE-NUTM2

Answer

The correct answer is B. In contrast, endometrial stromal nodules, tumors are circumscribed or at most may have ≤ 3 finger-like projections < 3 mm from the margin.

~2/3 of low-grade endometrial stromal sarcomas (LG-ESS) harbor gene fusions involving polycomb group genes.

• Most common gene fusions:

  • JAZF1-SUZ12 (most frequent)

  • JAZF1-PHF1

  • EPC1-PHF1

  • MEAF6-PHF1

• Rare gene fusions (<3 reported cases each):

  • MBTD1–EZHIP (CXorf67)

  • BRD8–PHF1

  • EPC2–PHF1

  • EPC1–SUZ12

• BRD8–PHF1 has also been reported in a high-grade endometrial stromal sarcoma

References: https://tumourclassification.iarc.who.int/chaptercontent/34/244

Case credit: UCSD Pathology

Author: Wangpan Jackson Shi, MD