Immunohistochemical expression analysis of inhibin-alpha and -beta subunits in partial and complete moles, trophoblastic tumors, and endometrial decidua

Analysis of PD-L1 expression in trophoblastic tissues and tumors

The immune checkpoint proteins, programmed death receptor 1 (PD-1) and programmed death ligand 1 (PD-L1), are crucial for maintaining fetomaternal immune tolerance and immune escape in cancers. In this study, we performed a comprehensive immunohistochemical study of PD-L1 expression in a large cohort of trophoblastic tissues and tumors. We found that normal villi and hydatidiform moles showed a heterogeneous PD-L1 staining among trophoblast (strong in syncytiotrophoblast, moderate in intermediate trophoblast, and weak/negative in cytotrophoblast). Eleven exaggerated placental sites (100%) showed variable PD-L1 staining, whereas 7 (36.8%) of 19 placental site nodules/plaques were weakly positive for PD-L1 (P < .001). All gestational choriocarcinomas (CCs; n = 63), epithelioid trophoblastic tumors (n = 12), and placental site trophoblastic tumors (n = 41) were PD-L1 positive, with most showing strong staining. However, PD-L1 expression was lower in epithelioid trophoblastic tumors compared with placental site trophoblastic tumors and CCs (P = .004). Three presumably germ cell-derived pure CCs, the CC elements in 13 mixed germ cell tumors, and 4 gastric/rectal CCs were also positive for PD-L1, with widespread staining. The background nontrophoblastic tissues, such as endometrial glands, squamous cells, and adenocarcinomas, were PD-L1 negative. Western blot analysis showed that PD-L1 was expressed in all 3 trophoblastic cell lines. We conclude that PD-L1 is a sensitive but nonspecific marker for trophoblast and related tumors. The frequent strong PD-L1 expression suggests that immune checkpoint blockade could be a promising approach in treating trophoblastic tumors that merits further investigation.

Proceedings of the 2018 National Toxicology Program Satellite Symposium

The 2018 annual National Toxicology Program Satellite Symposium, entitled "Pathology Potpourri," was held in Indianapolis, Indiana, at the Society of Toxicologic Pathology's 37th annual meeting. The goal of this symposium was to present and discuss challenging diagnostic pathology and/or nomenclature issues. This article presents summaries of the speakers' talks along with select images that were used by the audience for voting and discussion. Various lesions and other topics covered during the symposium included seminiferous tubule dysgenesis in rats, ameloblast and odontoblast degeneration/necrosis in a Sprague Dawley rat, intestinal leiomyositis in a beagle dog, gallbladder mucinous hyperplasia, focus of hepatocellular alteration and bile duct alteration in otters, renal tubule cytoplasmic vacuolation with basophilic granules in mice treated swith antisense oligonucleotide therapy, a uterine choriocarcinoma in a rhesus macaque, and rete ovarii proliferative ovarian lesions in various aged rat strains. One particularly provocative lesion was a malignant neoplastic proliferation in the renal pelvic region of a cynomolgus macaque from a 21-day study. Additional challenging lesions included thyroid proliferative lesions in zebra fish and gross findings in fish larvae during routine chemical screening. The Rabbit and Minipig International Harmonization of Nomenclature and Diagnostic Criteria Organ Working Groups also presented a series of challenging lesions.

The Utility of Immunohistochemistry in the Differential Diagnosis of Gynecologic Disorders

Context

Immunohistochemistry has assumed an increasing role in the identification and characterization of gynecologic disorders including lesions with deceptively bland morphology, uncommon and underdiagnosed neoplasms, and neoplasms with specific genetic alterations associated with overexpression or loss of expression of specific proteins. The diagnostic accuracy has been significantly improved owing to the discovery and increasing experience with the tumor-associated biomarkers, and the increasing demand for precise tumor classification to assess suitability for the expanding therapeutic modalities including clinical trials.

Objective

To differentiate lesions of the gynecologic tract through the use of effective immunohistochemical panels.

Data Sources

Literature review and authors' personal practice experience.

Conclusions

The application of diagnostic and prognostic immunohistochemical panels has enabled pathologists to better guide therapeutic decisions and to better predict the clinical outcome. It is now well established that the use of ancillary testing, including immunohistochemistry, has a significant power in the identification, differentiation, and classification of reactive, premalignant, and malignant gynecologic disorders. This article discusses the utilities and pitfalls of the commonly used immunohistochemical markers in the context of overlapping morphologic features encountered in the uterus, ovaries, and fallopian tubes.

Use of reticulin stain in the diagnosis of intra-uterine gestation

AIMS

The diagnosis of intra-uterine gestation may be problematic when specimens from clinically suspected products of conception lack chorionic villi and/or fetal somatic tissues, since the distinction of intermediate trophoblast from decidual or myometrial elements can be difficult. The placental site is also characterised by stromal changes, including the deposition of a characteristic extracellular fibrinoid matrix. We have noted that these stromal changes may be highlighted by a simple reticulin stain; therefore, we have evaluated reticulin staining in a series of endometrial biopsy specimens from patients with intra-uterine and ectopic gestations.

METHODS

Reticulin staining was performed in 28 endometrial specimens from patients with first trimester intra-uterine gestations, including 14 cases that lacked chorionic elements. Eight endometrial samples from patients with concurrent histologically verified tubal ectopic pregnancy were also examined. Selected cases were also studied using a Masson trichrome stain, and immunohistochemically with antisera to cytokeratin and HPL.

RESULTS

There was a distinct increase in reticulin staining, usually evident at low power magnification, in most areas of decidua showing implantation site. Prominent reticulin staining was present around the decidual and trophoblast cells and there was also accentuation around stromal vessels, glands and myometrial cells. There was no clear difference in staining within areas of decidua including only rare intermediate trophoblast cells but this pattern was seldom seen in isolation. Minimal changes were seen in the placental site using the Masson trichrome stain.

CONCLUSION

Reticulin stains may prove useful in the assessment of endometrial specimens from patients with purported intra-uterine gestations when chorionic elements are not identified. Since the staining technique is simple and can be quickly performed, it could be used as an adjunct to conventional H&E assessment and to select appropriate specimen blocks for additional more sensitive studies, including immunohistochemistry.

Second-trimester maternal serum markers in twin pregnancy with complete mole: report of 2 cases

We present second-trimester serum marker levels in cases of twin pregnancy with complete hydatidiform mole and a coexistent fetus (CHMCF). Second-trimester inhibin A (InhA) levels have not been previously reported in such cases. Second-trimester maternal serum screening, alpha-fetoprotein (AFP), unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and InhA measurements combined with maternal age to estimate a patient's risk of Down syndrome during pregnancy was performed as a routine prenatal test in 2 cases of CHMCF. Hospital records containing serum marker data, patient history, pathology reports, and pregnancy outcome were reviewed. In cases of CHMCF, maternal serum AFP and uE3 levels were similar to those of a normal singleton pregnancy, whereas hCG and InhA levels were markedly increased. Second-trimester maternal serum marker profiles in cases of CHMCF are a composite of normal singleton and molar tissue secretions. We have found, for the first time, that second-trimester InhA levels are markedly increased in these cases. Serum marker levels may be useful in diagnosis of CHMCF, prenatal counseling, and evaluation of risk for persistent trophoblastic disease.

The prognostic value of serum inhibin, 17 beta-estradiol and progesterone in cases of hydatidiform mole

The purpose of this study was to provide a diagnostic and a prognostic variable that could easily be measured in the laboratory, and that would predict the need for future therapy of persistent gestational trophoblastic disease. There would no longer be a need to treat all cases of hydatidiform mole prophylactically, to improve the outcome in only about 20% predicted to develop malignant gestational trophoblastic tumors. Circulating beta-human chorionic gonadotropin (beta-hCG), progesterone, 17 beta-estradiol and inhibin levels were measured using standard radioimmunoassays in 60 patients with complete hydatidiform mole and in 20 normal pregnant women of a corresponding duration of pregnancy and having a maternal indication for therapeutic abortion. There were no significant statistical differences between the two groups as regards gravidity, parity and gestational age. There was a significant statistical difference between patients with a molar pregnancy who developed gestational trophoblastic tumors (GTT) and those who did not develop GTT as regards pre-evacuation and follow-up mean serum beta-hCG, mean serum progesterone and mean serum 17 beta-estradiol levels. These findings together with the persistently elevated mean serum progesterone and mean serum 17 beta-estradiol levels at 6 weeks after evacuation in all cases who developed GTT suggested that progesterone as well as 17 beta-estradiol serum levels might be of prognostic value in cases of molar pregnancy. However, larger numbers of cases are required to correlate findings to beta-hCG serum level. Although mean serum inhibin level was significantly higher in women with hydatidiform mole than in normal pregnant women, it lacks any prognostic value for detection of subsequent gestational trophoblastic tumors.

Recent advances in immunohistochemistry in gynaecological pathology

Recent years have witnessed significant developments in the use of immunohistochemistry in diagnostic gynaecological pathology. This review details the most significant of these. In ovarian pathology, differential cytokeratin staining (CK7 and 20) assists in distinguishing between a primary ovarian adenocarcinoma and a metastatic adenocarcinoma, especially of colorectal origin. The development of markers characteristic of ovarian sex cord-stromal tumours (especially alpha-inhibin) facilitates diagnosis of these neoplasms which is often difficult by morphology alone due to the wide differential diagnosis. In the uterus, the distinction between a primary endometrial and endocervical adenocarcinoma may be facilitated by use of a small panel of antibodies, including CEA, ER and vimentin. Newly developed antibodies such as CD10 and h-caldesmon may be of use in the diagnosis of uterine mesenchymal lesions, especially in the distinction between endometrial stromal and smooth muscle lesions. Proliferation markers, such as MIB1, are of value in the cervix in the diagnosis of preinvasive squamous and glandular lesions. Recent studies have shown that cervical adenoma malignum exhibits a gastric phenotype. Advances have also been made in trophoblastic disease with the development of antibodies reactive against trophoblast such as alpha-inhibin, mel-Cam and p57. A newly developed monoclonal antibody HMGIC which is expressed in vulvovaginal aggressive angiomyxoma may prove to be of value in the often difficult distinction of this lesion from its histological mimics.