Carcinomas of the endometrium and ovary with undifferentiated components are uncommon neoplasms that are likely underdiagnosed. They are important to recognize as they have been shown to be clinically aggressive. We identified 32 carcinomas with undifferentiated components as defined by Silva and co-workers, 26 endometrial and 6 of ovarian origin. The patient age ranged from 21 to 76 years (median 55); 40% of patients were r50 years of age. Most patients (58% of endometrial and 83% of ovarian carcinomas with undifferentiated components) presented at advanced stages (FIGO III-IV). Pelvic and para-aortic lymph nodes were the most frequent sites of metastases. Twenty tumors, entirely undifferentiated, consisted of sheets of dyshesive, ovoid cells with uniform, large vesicular nuclei, whereas 12 tumors contained combinations of differentiated endometrioid adenocarcinoma with undifferentiated components. Although most undifferentiated tumors had a monotonous cytologic appearance without prominent stroma, six showed focal nuclear pleomorphism and eight cases had variably sized zones of rhabdoid cells in a background of myxoid stroma. The tumors were frequently misdiagnosed; they received a wide range of diagnoses, including FIGO grade 2 or 3 endometrioid carcinoma, carcinosarcoma, high-grade sarcoma including endometrial stromal sarcoma, neuroendocrine carcinoma, lymphoma, granulosa cell tumor and epithelioid sarcoma. Up to 86% of the cases showed focal, but strong keratin and/or epithelial membrane antigen staining, with CK18 being the most frequently positive keratin stain. They were predominantly negative for neuroendocrine markers, smooth muscle markers and estrogen receptor/progesterone receptor. Mismatch repair protein expression by immunohistochemistry was evaluated in 17 cases, and 8 (47%) were abnormal (7 with loss of MLH1/PMS2 and 1 with MSH6 loss). Follow-up was available for 27 patients, although it was very short in many cases, ranging from 0.5 to 89 months (median 9 months). Eleven patients (41%) died of the disease in 0.5-20 months, four are alive with disease and twelve patients have no evidence of disease. Endometrial and ovarian carcinomas with undifferentiated components have a broad histologic differential diagnosis, but they show specific histologic features that should enable accurate diagnosis. These tumors can occur in young women, may be associated with microsatellite instability and behave in a clinically aggressive manner.

Endometrial stromal tumors are uncommon mesenchymal tumors of the uterus. The classification of these tumors has evolved and the most current World Health Organization classification (2003) divides these neoplasms into: endometrial stromal nodule, low-grade endometrial stromal sarcoma, and undifferentiated endometrial sarcoma. The salient clinicopathologic features of these tumors are described, and a comprehensive review of literature pertaining to potential prognostic factors in endometrial stromal sarcomas is provided. Clinical factors, including age, race, parity and menopausal status, and pathologic factors, including tumor size, tumor stage, nuclear atypia, mitotic activity, tumor necrosis, lymphovascular space invasion, DNA ploidy and proliferative activity, and expression of hormone receptors, have been explored with varying outcomes. Surgicopathologic stage seems to be the most important prognostic factor in low-grade endometrial stromal sarcomas. The impact of other prognostic factors on survival is unclear or controversial, especially in patients with stage I tumors.

p16, a surrogate marker for human papillomavirus (HPV) infection, is uniformly present in HPV-related carcinomas. This study aims to further characterize p16 expression in trophoblastic lesions and squamous lesions of the upper female genital tract, as little data exists. p16 immunostaining was performed on sections from ichthyosis uteri (1), primary uterine corpus squamous cell carcinoma (UCSCC) (2), primary ovarian SCC (OSCC) (5; 2 associated with a dermoid cyst), endometrial endometrioid adenocarcinoma with extensive squamous differentiation (EC-SD) (5), ovarian endometrioid adenocarcinoma with extensive squamous differentiation (OC-SD) (4), placental site nodule (5), and placental site trophoblastic tumor (PSTT) (6). We evaluated the percentage of positive cytoplasmic and nuclear staining (focal ≤10%, multifocal=10% to 50%, and diffuse ≥50%) and staining intensity (weak, moderate, and strong). HPV-DNA analysis by polymerase chain reaction was performed on 5 OSCC. Ichthyosis uteri, all UCSCC and 1 OSCC (arising in a dermoid) were negative; the other dermoid-associated OSCC showed focal moderate staining, the remaining OSCC displayed strong (100%), diffuse (2), or multifocal (1) p16 positivity. Three of the 5 EC-SD cases showed strong diffuse staining of the squamous component. The glandular component focally showed strong p16 positivity (2), with variably intense focal staining in 3 cases. The squamous component of all OC-SD showed focal moderate staining, with variable staining of the glandular component. Overall, 3 EC-SD had 80% to 90% p16 positivity. Five of the 5 placental site nodules and 4 of the 6 PSTT showed focal weak staining, whereas 2 PSTT were p16 negative. HPV-DNA analysis was negative in 3 of the 5 OSCC, the other 2 cases being technical failures. p16 is expressed in OSCC and in the squamous and glandular components of EC-SD and OC-SD. As p16 is negative in UCSCC, it may help to identify the origin of SCC diffusely involving the corpus and cervix, and suggests different pathogeneses for SCC of the upper female genital tract, likely to be unrelated to HPV infection. In contrast to earlier data, we found weak and focal p16 expression in trophoblastic lesions. Thus, when considering the differential diagnosis of cervical SCC and trophoblastic lesions, only strong diffuse p16 staining should be considered helpful.

Neoadjuvant chemotherapy followed by interval debulking has become an alternative treatment option for patients with advanced-stage ovarian cancer. The effects of chemotherapy on the histologic features of the tumor have not been well described for ovarian carcinoma, especially related to changes that significantly alter the appearance of the tumor. In this study, we describe a case of ovarian serous carcinoma status-post neoadjuvant chemotherapy that showed exuberant clear cell/foamy change. This unusual morphology raised the possibility of a mixed epithelial carcinoma or a secondary malignancy. Immunohistochemical stains were performed to help distinguish whether the tumor was a serous carcinoma with chemotherapy-induced clear cell change or a distinct clear cell carcinoma of ovarian or extraovarian origin. The clear cell and conventional serous components showed diffuse positivity for CK7, CA125, and ER; however, only the clear cell component was positive for hepatocyte nuclear factor-1beta and only the conventional serous component was positive for WT1. Although there was a slight discrepancy in the staining patterns, given the lack of other typical histologic features of clear cell carcinoma, the unusual clear cell morphology was most likely the result of chemotherapy-induced changes.