Background/Aim: The diagnosis of gastric-type endocervical adenocarcinoma (GEA) is challenging because its differential diagnosis includes not only gynecological tumors, but also extragenital tumors. Patients and Methods: We reviewed the electronic medical records and all available slides to investigate the clinicopathological characteristics of eight misdiagnosed GEA cases. Results: Three tumors were initially misdiagnosed as endometrial carcinoma. They displayed extensive endomyometrial involvement and complex glandular architecture, but no severe nuclear pleomorphism. Another three tumors were misclassified as usual-type endocervical adenocarcinoma because of mucin-poor, pseudoendometrioid glands, apical mitotic figures, and karyorrhectic debris. The two remaining tumors presenting as adnexal masses mimicked primary ovarian mucinous tumor and metastatic cholangiocarcinoma. Conclusion: The varying pathological characteristics of GEA reflect the variability in clinical manifestations and its diagnostic difficulties. It is challenging to make an accurate diagnosis based solely on histological features. When suspecting GEA, clinicians should consider more comprehensively the clinicopathological context, along with immunostaining results.

We present herein a rare case of uterine serous carcinoma with mesonephric-like differentiation (SC-MLD) initially misdiagnosed as mesonephric-like adenocarcinoma (MLA). A 51-year-old woman underwent total hysterectomy for a uterine tumor. Histologically, the tumor exhibited various architectures, including papillary, glandular, tubular, cribriform, and cystic. On the basis of this architectural diversity accompanied by intraluminal eosinophilic secretions and intermediate-grade nuclear atypia, the initial diagnosis was MLA. However, the tumor was diffusely and strongly positive for the expression of p16 and negative for the expression of GATA-binding protein 3 (GATA3). Furthermore, we identified a pathogenic tumor protein 53 (TP53) mutation affecting an acceptor splice site in intron 9, despite a wild-type p53 immunostaining pattern. The observations of diffuse and strong p16 expression, lack of GATA3 expression, pathogenic TP53 mutation, and wild-type Kirsten rat sarcoma viral oncogene homolog indicate that this tumor was not an MLA but an SC-MLD. Both uterine SC and MLA can exhibit various histological growth patterns. Our comprehensive clinicopathological and molecular analyses can serve to improve the understanding of this rare condition and help pathologists in making an accurate diagnosis.

Background/Aim: We describe a rare case of ovarian mesonephric-like adenocarcinoma (MLA) involving the fimbria and mimicking serous tubal intraepithelial carcinoma (STIC). Case Report: A 47-year-old woman presented with a 4.4-cm left ovarian mass. Histologically, the ovarian tumor showed papillary and solid architecture, severe nuclear pleomorphism, and increased mitotic activity. Some microscopic foci where the tumor cells spread horizontally along the fimbrial surface epithelium were noted, compatible with STIC. We initially considered the ovarian tumor to be high-grade serous carcinoma accompanied by a fimbrial STIC. However, immunostaining revealed nuclear immunoreactivity for paired box 2 and GATA-binding protein 3, but lacked expression of Wilms tumor 1. A thorough slide review and additional immunostaining revealed architectural diversity, densely eosinophilic intraluminal secretions, and lack of hormone receptor expression, supporting the diagnosis of MLA. Conclusion: Microscopic intraepithelial metastases of the MLA to the fimbria mimic STIC. We recommend ancillary tests, such as immunostaining, in patients with ovarian tumors whenever possible, particularly for those with differential diagnosis of MLA and high-grade serous carcinoma.

Metastasis of extragenital malignancies to the female genital tract, particularly the uterus, is exceedingly rare. Invasive lobular carcinoma (ILC) is the most common histological type of breast carcinoma that metastasizes to gynecologic organs. A 42-year-old woman receiving tamoxifen presented with an irregularly thickened endometrium on transvaginal ultrasonography. She had previously undergone bilateral partial mastectomies - eight years prior for right-sided invasive ductal carcinoma, and three years prior for left-sided ILC. Hysteroscopic evaluation revealed an endometrial polyp. Microscopic examination of the polypectomy specimen showed variably sized, irregularly shaped branching glands embedded in densely fibrotic stroma. Within the stroma, monomorphic tumor cells with hyperchromatic, eccentrically located nuclei were arranged in single files, thin cords, or nests. Immunostaining revealed that the tumor cells were positive for GATA-binding protein 3 and negative for paired box 8, supporting a diagnosis of metastatic carcinoma from the breast. The final pathological diagnosis was metastatic ILC involving a tamoxifen-associated endometrial polyp. Although rare, breast carcinoma may metastasize to endometrial polyps. Clinicians and pathologists should consider this possibility when evaluating abnormal ultrasonographic findings in the female genital tract, particularly in patients with a history of breast carcinoma receiving tamoxifen therapy. Abnormal ultrasonographic findings in the uterus of such patients warrant a comprehensive diagnostic workup to exclude metastatic disease.

Dissecting gonadoblastoma (DGB) of the ovary, a recently described terminology, defines a unique distribution of neoplastic germ cells. Here, we report a case of incidental DGB coexistent with an atypical endometriotic cyst occurring in a 23-year-old woman. The ovarian cyst was lined by endometrial-like glands and stroma. Some glands displayed nuclear enlargement and hyperchromasia, and abundant eosinophilic cytoplasm with occasional intracytoplasmic hemosiderin and mucin vacuoles. The neoplastic germ cells resembled those of ovarian dysgerminoma and were diffusely distributed within the ovarian stroma, which was stretched around the wall of the endometriotic cyst. These cells were arranged in nests and cords, possessing clear cytoplasm and centrally located round nuclei with prominent nucleoli and occasional mitoses. Chromosomal analysis revealed a 46,XX karyotype. We describe the clinical, histological, immunophenotypical, and genetic features of ovarian DGB incidentally detected in the ovarian cystectomy specimen of a woman with normal female karyotype.