NTRK1/2/3 rearrangements have been identified as oncogenic drivers in a variety of tumors including those in the uterine cervix, and rarely, the uterine corpus. We report 2 cases of cervical sarcoma with NTRK gene rearrangements. Case 1 was a 54-yr-old woman who presented with postmenopausal bleeding and a 5.4 cm friable mass in the cervix. Microscopic examination of the tumor revealed proliferation of epithelioid and spindle cells arranged in alternating hypercellular and hypocellular areas, with subtle fibrosarcoma-like features. Coagulative tumor cell necrosis and readily recognizable mitoses (up to 40 mitotic figures per 10 high-power fields) were identified. Case 2 was a 52-yr-old woman who presented with abnormal vaginal bleeding and a 1.3 cm cervical mass. The resected cervical tumor showed proliferation of spindled cells with fascicular and storiform growth pattern, infiltrating into the smooth muscle with entrapment of normal endocervical glands. The tumor cells displayed mild cytologic atypia and low mitotic activity (1 mitotic figure per 10 high-power fields). The mixed inflammatory infiltrate was seen throughout the lesion, mimicking morphology of inflammatory myofibroblastic tumor. Immunohistochemical staining for S100 and CD34 demonstrated variable expression in case 1 and uniformly diffuse positivity in case 2. The tumor cells in both cases were focally positive for CD10, Cyclin D1, ER, and PR, and negative for AE1/AE3, desmin, SOX10, HMB-45. RNA fusion analysis identified SPECC1L-NTRK3 gene rearrangements in case 1 and TPM3-NTRK1 in case 2; DNA-based mutational analysis also revealed CDKN2A/B homozygous deletion in case 1. Despite accumulating literature on NTRK fusion mesenchymal tumors in gynecologic pathology, these tumors are still rare and lack well-established morphologic diagnostic criteria. Diagnostic and clinical recognition of these tumors is critical given the potential patient benefit from targeted therapy.

Purpose: Choriocarcinoma is most commonly gestational (androgenetic or biparental) but can be of germ cell origin or can develop as a component of a somatic neoplasm (genetically related to the patient). The latter type are aggressive neoplasms for which the underlying genetic alterations are not well characterized. Experimental Design: To investigate the relationship between the different components of somatic neoplasms with choriocarcinomatous elements, the genetic differences between gestational and nongestational tumors, and identify potential targetable alterations, we analyzed 23 samples from 11 tumors, including five gynecologic-type somatic neoplasms with choriocarcinomatous differentiation (two to three different components each) and six pure choriocarcinomas, for somatic mutations, single-nucleotide polymorphisms, and PD-L1 expression. Results: In mixed tumors, gynecologic-type carcinoma components demonstrated lineage-characteristic and lineage-specific alterations, with choriocarcinomatous components sharing some of these as well as demonstrating novel alterations, supporting a clonal relationship with divergent differentiation of the choriocarcinoma from the somatic carcinoma. TP53 mutation only occurred in nongestational tumors. Diffuse PD-L1 expression was characteristic of choriocarcinoma in both pure and mixed tumors but not seen in the gynecologic-type carcinoma components. Conclusions: Given that the somatic carcinomatous and choriocarcinomatous components of mixed tumors have distinct genetic alterations and biomarker expression, separate analysis of these components is required to guide targeted therapy. High PD-L1 expression suggests a role for checkpoint inhibitor–based immunotherapy in tumors with a choriocarcinoma component. The underlying mechanisms by which cancer stem cells reprogram and initiate trophoblastic retrodifferentiation in some somatic tumors warrant further investigation.

Aims: Mesonephric‐like adenocarcinoma (MLA) of the endometrium or ovary is a rare but distinct endometrial carcinoma which has a combination of characteristic morphological, immunohistochemical (IHC) and molecular features. SOX17 has been recently identified as a highly sensitive and specific marker for endometrial and ovarian carcinomas. In this study, we aimed to investigate SOX17 expression in MLA together with other IHCs to differentiate MLAs from other endometrial carcinomas.Methods: Seventeen previously diagnosed endometrial/ovarian MLAs were collected, and multiple IHCs were performed. Additionally, we performed SOX17, PAX8 and ER on tissue microarrays (TMAs) composed of 652 endometrial carcinomas from 2012 to 2015 when MLA diagnostic criteria were not established.Results: All 17 MLAs showed diffuse strong positive PAX8, negative ER and variable TTF1/GATA3 staining. Notably, all MLAs showed negative (n = 10) or focal weak/moderate (n = 7) staining for SOX17, which is more diffuse and stronger than PAX8 in other endometrial carcinoma subtypes. This finding prompted us to screen TMAs with 652 endometrial carcinomas diagnosed before MLA by an approach of combined SOX17 and PAX8 IHCs, and 14 cases with positive PAX8 but negative/focal weak SOX17 were identified. We further studied the 14 cases by examining morphology and performing additional IHCs (TTF1, GATA3, ER and CD10) and would classify seven (50%) of them as MLAs based on morphological features and positive CD10, TTF1 and/or GATA3 staining.Conclusion: Our results suggest that a combination of SOX17 and PAX8 IHCs would aid in diagnosing MLA if the results show strong positive PAX8, but negative SOX17.