Somatic Cancer Driver Mutation Analysis in Endometriosis with Tumor-like Presentations: A Case Series Study.

Background/

Objectives

Endometriosis manifests as ectopic endometrial tissue outside the uterine cavity. This lesion can sometimes appear at unusual anatomical sites or within the intestinal tract, growing and mimicking cancer. Such tumor-like endometriosis lesions are relatively uncommon and biologically intriguing.

Methods

This study is a retrospective case series of 14 patients presenting with tumor-like endometriosis at a single institution between 2007 and 2023. Laser capture microdissection was used to isolate epithelial cells from endometriotic glands in tissue sections from formalin-fixed, paraffin-embedded blocks, and the microdissected epithelium was analyzed for cancer driver mutations.

Results

Unlike conventional endometriosis, these tumor-like lesions were generally sizable and clinically presented in the groin area, aortic wall, omentum, bowel wall, or lymph nodes, all of which raised suspicion for malignancy, despite 11 (78.6%) of the 14 cases having a history of or clinical signs of endometriosis. A total of 11 cancer-driver mutations were identified in 6 of the 14 patients, with four patients harboring multiple mutations. Recurrent mutations included KRAS-activating mutations in four cases and ARID1A-inactivating mutations in two cases. Additional mutations involved PIK3CA, CTNNB1, CHD4, MYD88, and STAG2.

Conclusions

This study detected mutations in KRAS, ARID1A, PIK3CA, CTNNB1, and MYD88 in endometriotic lesions, consistent with previous literature, and identified newly reported mutations in CHD4 and STAG2. Not every tumor-like lesion harbored cancer driver mutations.