Croce, Sabrina

Low-grade endometrial stromal sarcomas (LG-ESS) are the second most common malignant uterine mesenchymal tumors, but in contrast to the more common leiomyosarcomas, they are often characterized by a prolonged and relatively indolent course. However, a subset of patients experience significant morbidity or die of disease, and it is difficult to predict which tumors will behave aggressively, with most published studies limited in either the number of tumors or the depth of pathologic parameters evaluated. Thus, we studied the clinicopathologic features of LG-ESS in 102 patients ranging from 21 to 74 (median: 47) years. All were treated with hysterectomy and staged according to both the FIGO 2018 system (stage IA=22, IB=36, I-not otherwise specified=5, II=16, III=13, IV=10) and the FIGO 1988 system (stage I=62, II=1, III=17, IV=22). Tumors measured 1.2-49 (median: 7) cm. Microscopically, 69 involved the endometrium while 33 were centered in the myometrium. Thirteen showed only minimal infiltration of the myometrium while the rest displayed the typical extensive myometrial permeation. The cervical stroma was involved in 18, the uterine serosa in 27, and the parametrium in 22. Conventional morphology resembling proliferative endometrial stroma was seen in 95, fibroblastic appearance in 35, smooth muscle differentiation in 23, sex cord-like differentiation in 21, stromal hyalinization in 21, and myxoid stroma in 9. Less common features included glandular differentiation resembling adenomyosis (n=5), pseudopapillary pattern (n=1), deciduoid appearance (n=2), adipocytic differentiation (n=2), multinucleated cells (n=2), and rhabdomyoblastic differentiation (n=1). Mitoses ranged from <1 to 20 per 10 high-power fields (median=3). Lymphovascular invasion and infarct-type necrosis were present in 64 and 23, respectively. Follow-up was available in all patients ranging from 16 to 358 (median: 79) months. Forty-six received adjuvant treatment as hormonal therapy (n=34), radiation (n=4), radiation and hormonal therapy (n=4), chemotherapy (n=3), or chemotherapy and radiation (n=1). Three patients had persistent unresected tumor following surgery, and an additional 34 had recurrences at intervals of 3 to 272 (median: 79) months, including 2 tumors with minimal infiltration. At last follow-up, 75 patients were alive with no evidence of disease, 14 were alive with disease, and 9 died of disease at intervals of 16 to 167 (median=70) months. Four died of unrelated causes without recurrence. Five-year recurrence-free survival (RFS) and disease-specific survival (DSS) were 80% and 94%, while 10-year RFS and DSS were 51% and 87%, respectively. On statistical analysis, cervical stromal involvement ( P =0.018) and myxoid stroma ( P <0.001) were associated with shorter recurrence-free survival. Tumors lacking a conventional component had worse disease-specific survival ( P =0.048). All other clinical and morphologic features, including stage, were not significantly associated with outcome. On multivariate analysis, only cervical stromal involvement remained an independent predictor of recurrence-free survival ( P =0.047; HR: 16.939) and no factors were independently predictive of disease-specific survival. Our findings highlight the difficulty in predicting outcomes in these tumors, likely due to slow progression and frequent treatment responses even in the recurrent setting. We confirm the potential for recurrence even in tumors initially showing minimal infiltration. Cervical stromal involvement and lack of conventional morphology are potential novel risk factors that should be further evaluated in subsequent studies.

We describe 22 examples of a novel, usually paratubal, adnexal tumor associated with Peutz-Jeghers syndrome in nearly 50% of cases that harbored STK11 alterations in all tested (n=21). The patients ranged from 17 to 66 years (median=39 y) and the tumors from 4.5 to 25.5 cm (median=11 cm). Most (n=18) were paratubal, with metastases noted in 11/22 (50%) and recurrences in 12/15 (80%). Morphologically, they were characterized by interanastomosing cords and trabeculae of predominantly epithelioid cells, set in a variably prominent myxoid to focally edematous stroma, that often merged to form tubular, cystic, cribriform, and microacinar formations, reminiscent of salivary gland-type tumors. The tumor cells were uniformly atypical, often with prominent nucleoli and a variable mitotic index (median=9/10 HPFs). The tumors were usually positive to a variable extent for epithelial (CAM5.2, AE1/AE3, cytokeratin 7), sex cord (calretinin, inhibin, WT1), and mesothelial (calretinin, D2-40) markers, as well as hormone receptors. PAX8, SF1, and GATA-3 were rarely positive, while claudin-4, FOXL2, and TTF-1 were consistently negative. All sequenced tumors (n=21) harbored alterations in STK11, often with a loss of heterozygosity event. There were no other recurrently mutated genes. Recurrent copy number alterations included loss of 1p and 11q, and gain of 1q, 15q, and 15p. Despite an extensive morphologic, immunohistochemical, and molecular evaluation, we are unable to determine with certainty the histogenesis of this unique tumor. Wolffian, sex cord stromal, epithelial, and mesothelial origins were considered. We propose the term STK11 adnexal tumor to describe this novel entity and emphasize the importance of genetic counseling in these patients as a significant number of neoplasms occur in association with Peutz-Jeghers syndrome.