No abstract

Cell-lineage-specific transcription factors are a group of regulatory proteins expressed in embryonic, differentiated, or neoplastic cells of the same lineage and represent a valuable repertoire of tissue-specific markers for the diagnosis of human tumors. Together with PAX2, PAX8 is a nephric-lineage transcription factor and is required for the establishment of renal-lineage cells and the formation of the kidney. In contrast to PAX2, little is known about the expression of PAX8 in adult kidney and renal tumors. In this study, we used immunohistochemistry to investigate the expression of PAX8 in adult human kidney and renal epithelial tumors. We report here that PAX8 was detected in renal epithelial cells in all segments of renal tubules from the proximal tubules to the renal papillae and in the parietal cells of Bowman's capsule in the adult kidney. PAX8 was also present in 98% of clear cell renal cell carcinomas (RCCs), 90% of papillary RCCs, and 95% of oncocytomas, similar to PAX2. In addition, PAX8 was found in 82% of chromophobe RCCs, 71% of sarcomatoid components of RCCs, and 100% (2/2) of renal medullary carcinomas. Overall, PAX8 was detected in 85% of metastatic renal tumors. Interestingly, expression of PAX8 was noted in some urothelial cells in the renal pelvis and ureters and B23% of urothelial carcinomas of the renal pelvis, but not in the urothelium or urothelial carcinomas of the urinary bladder; this probably underlines the different embryonic origins of urothelial cells in the upper and lower urinary tracts. As shown in this study, PAX8 is widely expressed in normal and neoplastic renal tissues. PAX8 may be a useful additional marker for renal epithelial tumors; however, its specificity and sensitivity await further investigation.

Third-trimester placentas of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive women: histomorphology, including viral immunohistochemistry and in-situ hybridization Aims: The wide variety of affected organ systems associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection highlights the need for tissue-specific evaluation. We compared placentas from SARS-CoV-2-positive and SARS-CoV-2negative women in our hospital in New York City, which became the epicenter of the coronavirus disease 2019 pandemic in March 2020. To date, some limited studies have been published on placentas from SARS-CoV-2-positive women. The aim of our study, in addition to describing histomorphology, was to utilize in-situ hybridization (ISH) for the S-gene encoding the spike protein and immunohistochemistry (IHC) with the monoclonal SARS-CoV-2 spike antibody 1A9 for placental evaluation. Methods and results: In this study, 51 singleton, third-trimester placentas from SARS-CoV-2-positive women and 25 singleton, third-trimester placentas from SARS-CoV-2-negative women were examined histomorphologically according to the Amsterdam Criteria and with ISH and/or IHC. The corresponding clinical findings and neonatal outcomes also were recorded. Although no specific histomorphologic changes related to SARS-CoV-2 were noted in the placentas, evidence of maternal-fetal vascular malperfusion was identified, with placentas from SARS-CoV-2-positive women being significantly more likely to show villous agglutination (P = 0.003) and subchorionic thrombi (P = 0.026) than placentas from SARS-CoV-2-negative women. No evidence of direct viral involvement was identified with ISH and IHC. Conclusions: In this study, third-trimester placentas from SARS-CoV-2-positive women were more likely to show evidence of maternal-fetal vascular malperfusion; however, ISH and IHC provided no evidence of direct viral involvement or vertical transmission.

There is substantial overlap in the imaging characteristics of benign and malignant phyllodes tumors. A tumor diameter of 3 cm or greater appears to be associated with a higher likelihood of malignancy.

PAX2 is a urogenital developmental transcription factor expressed in the Wolffian ducts, developing kidneys, and Mü llerian ducts during embryonic stage. Its function in renal development is well documented and its clinical application in the diagnosis of lesions of renal origin has been reported recently. However, information on its role in the Mü llerian-derived genital tract is sparse. In this study, we investigated the expression of PAX2 in human female genital tract using immunohistochemistry. We demonstrated that PAX2 was expressed specifically in the epithelial cells of fallopian tube, endometrial and endocervical glands, but not in the stromal tissues in these areas. PAX2 was detected in secondary Mü llerian structures in the ovary, such as endometriotic and endosalpingiotic glands and rete ovarii, but not in ovarian surface epithelium, surface epithelium-derived inclusion cysts, stroma, or sex-cord-derived structures such as follicles, oocytes, and corpus luteum. In addition, PAX2 was detected in 67% of ovarian papillary serous carcinomas (N ¼ 36) but rarely in peritoneal malignant mesotheliomas, with two exceptions (N ¼ 54). Interestingly, the two PAX2-positive 'peritoneal malignant mesotheliomas' were from female patients and were positive for estrogen receptor. The significance of expression of PAX2 and estrogen receptor in these cases is under investigation. Taken together, we suggest that PAX2 is a novel Mü llerian-specific epithelial marker when used in proper clinical settings. Identification of PAX2 in the majority of papillary serous carcinomas of the ovary but not in the ovarian surface epithelium or epithelium-derived inclusion cysts suggests that this malignant epithelial tumor may be directly derived from the primary or secondary Mü llerian epithelium in or surrounding the ovary, rather than from the surface epithelium or its derivatives.

The results strongly suggest that papillary lesions diagnosed as benign at core-needle biopsy should be surgically excised because a substantial number of lesions were upgraded to ADH and DCIS at excision.

No abstract

Benign and malignant papillary lesions of the breast can be reliably diagnosed at SDVAB when the SDVAB results correlate with the imaging findings. However, the extent of malignant papillary disease may be underestimated at SDVAB; in our study, invasive carcinoma was later discovered in 25% of patients with this diagnosis.