Atypical Placental Site Nodule Arising in a Postcesarean Section Scar: Case Report and Review of the Literature.

The distinction between benign and malignant trophoblastic lesions often presents a diagnostic challenge, even in entities with defined morphologic and immunohistochemical criteria. Lesions arising from chorionic-type intermediate trophoblast, namely placental site nodule (PSN) and epithelioid trophoblastic tumor (ETT), can be distinguished by existing criteria. However, a putative intermediate lesion termed "atypical placental site nodule" (APSN) has been described in the literature but is not well-classified. We present a case of APSN, along with a brief literature review, and we propose more definitive morphologic and immunohistochemical criteria for this entity, in order to facilitate easier diagnosis and gather more information regarding outcomes.

Gastric-Type Endometrial Adenocarcinoma: Report of Two Cases in Patients From the United States.

Gastric-type adenocarcinomas of the uterine cervix have been described within the literature in detail; however, the description of gastric-type endometrial adenocarcinomas is a recent development, with only two cases originating from Japan in the world literature to date. According to these prior reports, the recognition of this pattern of differentiation is critical, as it is often associated with deep myoinvasion, positive regional lymph nodes, and poor outcome despite appropriate adjuvant treatment. We present two cases of endometrial adenocarcinoma with gastric-type differentiation in patients from the United States with superficial myoinvasion and positive patient outcomes. Gastric-type differentiation in endometrial adenocarcinomas is rare and likely underrecognized. Continued reporting of these cases is necessary to further understand the natural history and clinical implications of this entity.

Persistence of Villous Immaturity in Term Deliveries Following Intrauterine Transfusion for Parvovirus B19 Infection and RhD-associated Hemolytic Disease of the Fetus and Newborn.

Common causes of fetal anemia and hydrops include parvovirus B19 infection during the first 2 trimesters of pregnancy, as well as maternal alloimmunization to RhD with subsequent hemolytic disease of the fetus and newborn (HDFN) in an RhD positive fetus. Although both of these conditions have historically caused significant fetal morbidity and mortality, the advent of intrauterine transfusion (IUT) over the last few decades has dramatically improved outcomes. Prior literature has extensively documented placental changes associated with untreated parvovirus infection and RhD HDFN in intrauterine fetal demises and preterm births; however, histopathologic changes in term placentas from term infants treated with IUT have not been reported. We present placental findings in 2 cases of parvovirus B19-associated hydrops and 2 cases of RhD HDFN-associated hydrops in term infants after IUT, highlighting unique aspects that may be diagnostically useful for the examining pathologist.

Ovarian Yolk Sac Tumor With High-Grade Serous Carcinoma in a 62-Year-Old Woman.

Ovarian yolk sac tumors are germ cell tumors that usually present in children and young women. Rarely, these tumors can arise in older women, usually in conjunction with surface epithelial tumors, suggesting divergent differentiation from the latter. The combination of mixed ovarian yolk sac tumor and high-grade serous carcinoma is rare, with only one case documented in the literature. We present a case of mixed ovarian yolk sac tumor and high-grade serous carcinoma in a postmenopausal woman, including a brief discussion of the immunohistochemical findings and differential diagnosis. Despite the rarity of mixed ovarian yolk sac tumor and surface epithelial tumors, it is important to recognize the biphasic nature of the tumor, which should prompt a thorough immunohistochemical evaluation. The therapeutic and prognostic implications of proper diagnosis cannot be overemphasized.

Intraparotid schwannoma.

Diagnoses most commonly associated with a unilateral parotid mass include sialadenitis, pleomorphic adenoma, Warthin tumor, and mucoepidermoid carcinoma. However, rare entities, such as intraparotid schwannoma, must be considered in the differential diagnosis. We present a brief literature review that is illustrative of the current difficulty of preoperative diagnosis of intraparotid schwannoma, which is an exceptionally rare entity, with approximately 80 cases described to date. It may mimic common neoplasms and inflammatory salivary gland conditions on fine-needle aspiration and imaging, but is more likely to be associated with the facial nerve. Depending upon the tumor's spatial relationship to the facial nerve and the extent of neurologic dysfunction, the decision may be made to observe the tumor rather than attempt resection. This potential implication for patient management is a critical consideration that highlights the need for timely, appropriate biopsy and diagnosis.