Non-Fusion Mutations in Endometrial Stromal Sarcomas: What is the Potential Impact on Tumorigenesis through Cell Cycle Dysregulation?

Targeted next-generation sequencing using the 50-gene Ion AmpliSeq Cancer Hotspot Panel v2 identified two significant point mutations in endometrial stromal sarcomas (ESS). Case 1 is a uterine mass from a quadragenarian woman with a karyotype lacking any known ESS rearrangements but demonstrated to have a CTNNB1-activating mutation (c.133T>C, p.[Ser45Pro]). Analysis of a uterine mass from case 2, a sexagenarian woman, revealed biallelic CDKN2A-inactivating mutations (c.172C>T, p.[Arg58Ter] and a deletion). Break-apart studies to identify YWHAE, JAZF1 and PHF1 rearrangements were negative in both tumours. We propose a model in which these point mutations may affect cell proliferation, converging at Wnt signalling and G1-S checkpoint control, that independently or in concert with a rare gene fusion result in ESS tumour development or progression