Distinct Histologic, Immunohistochemical and Clinical Features Associated With Serous Endometrial Intraepithelial Carcinoma Involving Polyps.

The origin of serous endometrial intraepithelial carcinoma (SEIC) is debated, due to its premalignant and independently malignant nature. It often arises next to endometrial serous carcinoma (ESC), with a propensity for polypoid growth. We aimed to better characterize this discrepancy by analyzing the clinical, histologic, and immunohistochemical features of polypoid carcinoma associated with SEIC (P-SEIC), and compared them with usual endometrial serous carcinoma without SEIC (UESC). Consecutive patients with P-SEIC were recruited and compared with UESC controls from our institutional research center. Clinical, histologic, and immunohistochemical (IHC, ER, PR, P53, Napsin-A, WT1, P16) were analyzed. BRCA testing results and familial history were also extracted from clinical databases. Welch T test, Pearson χ, and Fisher exact test were performed in SPSS version 23. A total of 37 P-SEIC and 25 UESC were the basis of a case-control study. P-SEIC was associated with more bilateral ovarian involvement (P=0.026), yet showed lower rates of myometrial invasion (P=0.002). P-SEIC showed a statistically different IHC profile: p53+, p16+, ER+, PR+, and WT-1+, and high rates of Napsin-A, while UESC was p53+, p16+, WT-1-, Napsin-A-, with lower rates of ER and PR. We also identified 2 patients who received prophylactic salpingo-oophorectomy for BRCA mutations and who subsequently developed P-SEIC with its unique IHC pattern. Our results suggest different underlying expression profiles and possibly diverging molecular signatures between both P-SEIC and UESC. If confirmed in further molecular studies, it could lead to a distinct molecular subclass.

Microcystic, elongated, and fragmented pattern invasion is mainly associated with isolated tumor cell pattern metastases in International Federation of Gynecology and Obstetrics grade I endometrioid endometrial cancer.

Although many studies have evaluated the impact of mismatch repair protein loss of expression (MMR LOE) or microcystic, elongated, and fragmented (MELF) pattern of myometrial invasion as individual factors in endometrial cancer, we analyzed the combined impact of both. We reviewed every case of International Federation of Gynecology and Obstetrics (FIGO) grade 1 endometrioid endometrial cancers (EECs) from our institution, between 2011 and 2015, that had a sentinel lymph node biopsy and/or a lymphadenectomy, and examined the following data: age, myometrial infiltration, MELF infiltration, lymphovascular space invasion, and lymph node status. These cases were then grouped according to the absence of lymph node metastases, the presence of isolated tumor cell (ITC) lymph node metastases, or the presence of non-ITC metastases. Among the 127 cases that were in our study, 105 patients did not have nodal metastases, whereas 22 patients showed metastases, of which 11 were ITC. MMR LOE was only significantly associated with a higher odds ratio (OR) of metastases (OR, 7.44; P < .001). MELF was only associated with a higher OR of ITC-pattern metastases (OR, 32.3; P < .001). This study distinguished the effects of MELF and MMR LOE on the risk of metastases in FIGO grade 1 EEC. Further research on the clinical impact of MELF and ITC-pattern metastases is warranted to better guide clinicians on the management of patients with FIGO grade 1 EEC harboring such characteristics, which are still considered low-risk cancer.