Hepatic (hepatocellular) adenoma of the placenta: a study of four cases

Heterotopic Hepatic Tissue in the Placenta: A Case Report

Heterotopic hepatic tissue in placenta or umbilical cord is rare. The exact mechanism by which this heterotopia occurs has not been fully understood but is thought to be related to yolk sac primordia. To date, a handful of such cases have been reported. We present a case of heterotopic liver tissue within a chorionic stem villus of a 37 week-growth restricted neonate and describe the tissue morphology and its immunohistochemistry workup.

Intraplacental Hepatic Heterotopia

Background: Placental hepatic heterotopia is a benign lesion with unclear histogenesis hypothesized to be of hepatocytic differentiation of yolk sac elements. Of the 14 hepatic heterotopia cases previously reported, 12 cases occurred in preterm labor.Case report: A case of intraplacental hepatic heterotopia in a 27-year-old female with pre-term delivery at 31 + 5 weeks gestational age is described. Histopathological examination revealed a well-demarcated lesion with cohesive, monotonous cells and pale to clear cytoplasm. The differential diagnoses of this lesion included benign, primary and metastatic malignant entities. The lesional cells expressed HepPar-1, CAM 5.2, Glypican-3, and AFP, consistent with cells of hepatic origin.Conclusion: Intraplacental hepatic heterotopia is associated with premature labor. Distinguishing this lesion from maternal and fetal malignancies with similar histopathological presentation has important clinical implications in patient care.

Ectopic Fetal Liver Tissue in the Placenta of a Twin Pregnancy: A Case Report and Review of Literature

Ectopic liver tissue represents a rare entity and is mostly attributed to events occurring during embryogenesis. Previous case reports documented the presence of fetal liver parenchyma within temporarily developed organs during pregnancy, such as the placenta or the umbilical cord. Moreover, the terminology of these benign findings varies from “ectopic liver” to “hepatocellular adenoma-like neoplasm” or “hepatocellular adenoma”. Ancillary tests performed on these lesions have shown positive immunohistochemical staining for hepatocellular origin marker HepPar-1. Only one recent case report comprising molecular analysis showed no beta-catenin gain-of-function mutation. We report a case of ectopic liver in one placenta of a twin pregnancy, with an updated review of literature.

Mixed chorangioma and leiomyoma of the placenta, with a brief review of nontrophoblastic placental lesions

Chorangioma is the most common type of primary non-trophoblastic tumor of the placenta, usually identified incidentally on ultrasound or at delivery. Leiomyomas within the placenta have been described, though they are rare and usually of maternal origin. We present an unusual case of a placental tumor with combined histopathologic and immunohistochemical features of both chorangioma and leiomyoma. A 39-year-old woman was found to have an echogenic placental mass at 33 weeks of gestation on ultrasound, that was thought to be a chorangioma. They followed up weekly, and performed a cesarean section at 39 weeks, due to concern for intrauterine growth restriction. No fetal or maternal complications occurred. Grossly, a 9-cm, red-brown mass with a broad-based stalk was identified on the fetal surface of the placenta near the periphery. Microscopically, the lesion was found to display characteristic features of chorangioma, with vascular proliferation, which stained positive for CD34 and CD31. SMA and caldesmon immunohistochemical staining was also positive, highlighting the proliferation of smooth muscle throughout the neoplasm. Literature review revealed a single additional case with similar characteristics.

Hepatic and Adrenocortical Choristomas in the Placenta

Background Hepatic and adrenocortical choristomas are unusual findings in the placenta. This meta-analysis includes our own case report and 23 previously reported cases. We searched for patterns of associated placental, fetal and maternal aberrations in order to determine whether these choristomas are clinically relevant. Case report: In our case, abortion was induced due to fetal central nervous system and renal malformations. In the placenta a hepatic choristoma (<0.1 cm), thrombangiitis obliterans and a single umbilical artery were found. Results: In the literature, the majority of lesions were ≤1.0 cm (n = 21/24, 87.5%) and two hepatic choristomas manifested within chorangiomas. In a subfraction of cases, we found an association with twin/triple pregnancies (n = 6/24, 25%) and heterogeneous non-hepatic/non-adrenal malformations in fetuses (n = 4/24, 17%). Conclusion: Hepatic and adrenocortical choristomas are benign, could be based on focal epigenetic changes and might be related to chorangiomas but are not associated with a particular disease pattern or risk profile.

Heterotopic Adipose Tissue in the Placental Parenchyma: Case Report

Objective: Reports of heterotopic tissue in the placenta are few and mainly include liver and adrenal cells. We report on adipose tissue found in the placenta. Case report: We present the case of a microscopic finding in a 25-year-old's placenta who suffered from hypertensive disorder in pregnancy. During routine microscopic study, we observed a heterotopic, benign, circumscribed and intervillous nodule of adipose tissue. Conclusion: To our knowledge, there is no other reported case of adipocytes among chorionic villi. Why foreign tissues show up in the placenta remains unknown; however, several new theories offer explanations.

Fetal Origin of Placental Hepatic Nodule

Intraplacental hepatic nodules are extremely rare and range from incidentally identified microscopic nodules to large mass-forming lesions. We describe the case of an incidentally identified intraparenchymal hepatic nodule in the placenta from a near-term delivery of a male infant at 36 weeks gestation. Lesional cells were positive for HepPar1, focally positive for glypican3, and negative for calretinin and alpha-fetoprotein, supportive of hepatocellular origin. Fluorescence in-situ hybridization and chromosomal microarray both showed a male sex chromosome complement (XY) within the nodule, confirming the fetal origin of this nodule. We provide the first report of the confirmed fetal origin of these rare lesions, lending support to the hypothesis that placental hepatic nodules may represent an embryonal rest or residua of abnormal cell migration.

Heterotopic Nodules in the Placenta, an Immunohistochemical Re-evaluation of the Diagnosis of Adrenocortical Heterotopia

BACKGROUND

Rare nodules of heterotopic adrenocortical and hepatic tissue are reported in the placenta. A mechanism for adrenocortical tissue in the placenta has been perplexing, while hepatic tissue is generally considered related to yolk sac primordia. The clear cell morphology of these nodules is similar to the adrenal cortex of the adult; however, the fetal adrenal gland does not usually display clear cells.

METHODS

We stained 9 placental nodules, histologically identical to "adrenocortical" heterotopia of the placenta, to determine whether adrenocortical differentiation could be confirmed. These cases include 3 archival cases initially diagnosed as "adrenocortical" heterotopia.

RESULTS

Immunohistochemical staining with steroid factor-1 (SF-1), HepPar-1, and Arginase-1 showed that these nodules of clear cells are actually hepatic (SF-1 negative, HepPar-1, and Arginase-1 positive). PAS staining suggests that glycogen accumulation is responsible for the clear cytoplasm. In contrast, a nodule of adrenocortical heterotopia near the testis and the adrenal gland from a 38-week-old neonatal autopsy case confirm SF-1 reactivity as expected.

CONCLUSION

We propose that adrenocortical heterotopia in the placenta is a misnomer, and that these subchorionic nodules of clear cells demonstrate hepatic differentiation.

Ectopic Fetal Hepatic Tissue in the Placenta

When an unusual intraplacental lesion is identified during pathologic examination, it becomes of substantial import to determine whether it represents a normal structure, metastasis from the mother, or a primary benign tumor, including those secondary to abnormal embryologic development versus a primary malignant placental tumor. In this case report, we identified an incidental nest of intraplacental cells with nondiagnostic morphology and negative initial Glypican-3 stain in a healthy 35-wk gestation. This negative result prompted a broadening of the differential before ultimately determining this lesion was indeed ectopic liver with positive Arginase-1 and HepPar-1 staining. This may represent the mature hepatocyte phenotype within the lesional cells of this near-term birth, a dichotomy not previously discussed in the literature, which focuses on the fetal hepatocyte phenotype, also rarely seen. In this report, we summarize the previous literature regarding intraplacental ectopic liver, and we propose a sensitive approach to suspected ectopic liver of the placenta that may be sufficient to capture both the fetal and mature hepatocyte immunophenotypes. This approach may extend to other related pathologies including assessment of suspected intraumbilical hepatocytes.

Uterine inflammatory myofibroblastic tumors in pregnant women with and without involvement of the placenta: a study of 6 cases with identification of a novel TIMP3-RET fusion

Uterine inflammatory myofibroblastic tumors (IMTs) have been reported in association with pregnancy and, in some instances, secondarily involve the placenta. The clinicopathological spectrum of these tumors in the setting of pregnancy is not well defined. We investigated the clinical, morphologic, immunohistochemical, molecular cytogenetic, and genetic features of 6 uterine IMTs occurring in pregnant women. Each tumor was discovered at parturition, and none was identified by prenatal ultrasound. Patient age ranged from 25 to 41 years (mean 31.5). Tumor size ranged from 1.5 to 9 cm (mean 4.7). Four of 6 had usual IMT features, with at least focal deciduoid change in 3. Necrosis was identified in 3 tumors; and multinucleated cells, in 3 tumors. Sex hormone receptor expression was consistent with estrogen receptor negative or focally weakly positive and progesterone receptor diffusely moderately or moderately to strongly positive in all 6 tumors. ALK immunohistochemistry was strongly positive in 5 tumors, and all of these had an ALK rearrangement detected by break-apart fluorescence in situ hybridization. Subsequent RNA sequencing of these 5 tumors identified a TIMP3-ALK fusion in 4 and a THBS1-ALK in 1. In the ALK-negative tumor, RNA sequencing detected a novel TIMP3-RET fusion that was confirmed by RET break-apart fluorescence in situ hybridization. Follow-up was available for 2 of 6 patients 5 and 19 months after diagnosis. Neither patient developed recurrence. ALK immunohistochemistry will distinguish most uterine IMTs, but if ALK expression and gene studies are negative, in the appropriate morphologic context, evaluation of other tyrosine kinase genes known to be more commonly altered in extrauterine IMTs such as ROS1, NTRK3, PDGFRβ, and RET may be necessary for diagnostic confirmation.

A first case of hepatocellular carcinoma in the baboon (Papio spp.) placenta

We present a case of hepatocellular carcinoma (HCC) in the placenta of healthy baboon (Papio spp.). Grossly, the fetal, maternal, and placental tissues were unremarkable. Histologically, the placenta contained an unencapsulated, poorly demarcated, infiltrative, solidly cellular neoplasm composed of cells that resembled hepatocytes. The neoplastic cells were diffusely positive for vimentin and focally positive for Ae1/Ae3, Arginase -1, glutamine synthetase, and CD10, and negative for ER, vascular markers (CD31 and D240), S100, glypican, C-reactive protein, FABP, desmin, and beta-catenin; INI1 positivity was similar to non-neoplastic tissues. The case likely represents a unique subtype of HCC.

Ectopic Liver Within the Placental Parenchyma of a Stillborn Fetus

Rarely, liver tissue can be seen in the umbilical cord, where it is thought to result from ectopic localization during embryogenesis. The placental parenchyma is also a rare site for this occurrence. The exact pathophysiology of ectopic liver in the placenta is unknown. It has been considered that aberrant migration or displacement of cells from the developing hepatic buds leads to ectopic liver formation, including groups of liver cells that become entrapped in the foregut as the diaphragm closes. Additional hypotheses put forward have included monodermal teratoma and hepatocellular adenoma. While the lesions may not actually be adenomas, this term has been most utilized in the literature. Hepatocellular adenomas of the placenta are extremely rare; only 9 cases have been reported thus far. We report an additional occurrence of ectopic liver in the placenta, which is the only one reported in a stillborn, and review the literature.

Hepatocellular Adenoma of the Placenta With Updated Immunohistochemical and Molecular Markers

We describe the clinicopathological, immunohistochemical, and molecular features of an unusual case of a hepatocellular adenoma of the placenta presenting as a subchorionic intervillous mass lesion in a diamnionic dichorionic placenta. A well-circumscribed 0.8 cm round nodule was identified in one of the twin placental discs, wherein, on microscopic review, the lesional cells morphologically and immunophenotypically resembled fetal hepatocytes. Given the rarity of this lesion, we performed an updated immunohistochemical and molecular analysis, including makers for β-catenin activation and well-differentiated hepatocellular carcinoma, and the results support the notion that hepatocellular adenoma of the placenta is a benign incidental finding.

Pseudotumors of the placenta

The placenta is one of the most common gross pathology specimens encountered by surgical pathologists, yet primary tumors are exceptionally rare and even rarer are entities with the potential to mimic malignancy. There are many nonneoplasticmass forming lesions in the placenta that are important to be aware of as many of these can be associated with adverse outcomes in the mother and fetus. Also important are entities which may be observed microscopically in the placenta and potentially confused as a malignancy. Knowledge of these potential pitfalls is essential to avoid making an incorrect diagnosis and causing undue alarm.

Coexistent Chorangioma and Hepatic Adenoma in One Twin Placenta: A Case Report and Review of the Literature

Primary nontrophoblastic tumors of a placenta are very uncommon, with the majority being of vascular origin, such as chorangiomas and chorangiomatosis. Rare examples of tumor-like collections of liver tissue, morphologically consistent with hepatocellular adenomas, have been reported. We report the co-occurrence of a chorangioma and hepatic adenoma as a grossly single lesion on the fetal surface of a diamniotic dichorionic twin placenta.

A diagnostic immunohistochemical panel for yolk sac (primitive endodermal) tumours based on an immunohistochemical comparison with the human yolk sac

AIMS

To establish a diagnostic immunohistochemical panel for various histotypes of yolk sac (primitive endodermal) tumours (YSTs) by comparison with the human yolk sac (HYS) immunophenotype.

METHODS AND RESULTS

Twenty-five YSTs showing either classical patterns (CPs) of histology (microcystic/reticular, n = 14; polyvesicular, n = 1; and hepatoid, n = 1) or somatic glandular patterns (SGPs; n = 9) were analysed for expression of α-fetoprotein (AFP), glypican-3 (GPC3), villin, hepatocyte paraffin-1 (HepPar-1), CDX2, SALL4 and LIN28. AFP expression was constantly heterogeneous in CPs but tended to be focal/absent in SGPs. GPC3 was diffuse in CPs but heterogeneous (seven cases) or focal/absent (two cases) in SGPs. HepPar-1 expression was focal in all but three cases (diffuse in one CP-hepatoid and two SGPs). CDX2 positivity was focal in CPs but heterogeneous (seven cases) or diffuse (two cases) in SGPs. Villin, SALL4 and LIN28 were diffusely positive in nearly all cases.

CONCLUSIONS

CPs reproduce the immunophenotype of HYS and early endoderm with variable expression of both AFP and markers of early gut or hepatic differentiation. SGPs with intestinal differentiation often have incomplete immunophenotypes. A differential diagnosis panel, including both markers of pluripotentiality (SALL4 and/or LIN28) and endoderm (AFP, GPC3 and villin), is proposed. It identifies overlapping multidifferentiation of primitive and somatic immunophenotypes, supporting the recently proposed term of primitive endodermal tumours.

Growth patterns of placental and paraovarian adrenocortical heterotopias are different

Two cases of adrenocortical heterotopia are reported. One is in a full-term placenta. The other is adjacent to the ovarian hilum of an adult. Both are incidental findings. Despite sharing similar histological and immunological features, they show different growth patterns. The literature is reviewed and adrenocortical heterotopias of different locations are compared. New hypotheses of its histogenesis are discussed.

Placental pathology, a survival guide

Placental pathology continues to be an underutilized, undertaught, and inadequately handled surgical subspecialty. The requests for placental pathology are soaring, due partly to demands from obstetricians and to the litigious environment in which they practice, and to improved obstetrical care leading to pregnancies in medically challenging situations. Evaluation of the placenta requires a good understanding of the questions and issues concerning both the fetus/infant and the mother. Information from placental pathology can be critical in early neonatal care and in reproductive planning for the family, and it can provide risk assessment for neurologic outcome of the infant. A comfortable interaction among the obstetric staff, mothers, and pathologists often obviates need for legal intervention in unexpected pregnancy outcomes. Some critical pathologic features that involve maternal and fetal management are illustrated herein. A template for gross examination and a few critical histopathologic diagnostic features with clincopathologic correlation are included.

Clinical significance of placental examination in perinatal medicine

Complete pathologic evaluation of the placenta provides valuable information for perinatal care for the obstetrician, neonatologist, pediatrician, and family. The histopathology of the placenta can answer specific questions about in utero insults, give insight into management of subsequent pregnancies, and provide an assessment of the newborn risk. Placental pathology has been a key litigious informant in inferring timing of insults. Despite these well known advantages of placental pathologic examination, it remains an under-utilized part of perinatal medicine. This stems from a historically under-taught part of surgical and autopsy pathology resulting in inadequate reporting. This review will focus on the utility of the placental examination for fetal and maternal well-being. This review will be restricted to singleton births.

Placental Yolk Sac Tumor With Divergent Endodermal Differentiation

We report an intraplacental germ cell tumor that was an incidental finding in the placenta of a 34-year-old woman. On pathologic examination, the 4.0-cm tumor was well circumscribed with a thin fibrous capsule. It exhibited three major histologic patterns within a mesenchyme-like myxoid background: a primitive endodermal component, a well-differentiated enteric glandular endodermal component, and a component of fetal hepatic tissue. The primitive endodermal component, the hepatic component, and many parts of the enteric endodermal glandular component were immunoreactive for alpha-fetoprotein. We considered the lesion to be a unique example of a placental yolk sac tumor and only the second reported case of a placental yolk sac tumor.

Placental findings after laser ablation of communicating vessels in twin-to-twin transfusion syndrome

As laser ablation of placental vascular communications gains acceptance as treatment option for severe twin-to-twin transfusion syndrome (TTTS), pathologists are increasingly confronted with the interpretation of laser-treated placentas. We present our preliminary institutional experience with the gross and microscopic analysis of these specimens. Patients underwent selective ablation for severe TTTS (Quintero stages II to V) between 16 and 25 wk gestation and the placentas were examined between < 24 h and 19 wk postoperatively. The placental vasculature was injected with gelatin-dye mixtures. The type and number of vascular anastomoses were recorded, followed by routine histopathological analysis of the placenta. Foci of laser impact were identified in all placentas examined within 1 month after laser coagulation. Located along the recipient side of the dividing membrane, the laser-treated vessels appeared hemorrhagic and showed a characteristic abrupt interruption of dye filling after vascular injection. In placentas examined more than 1 month after intervention, the most frequent gross finding was the absence or relative paucity of intertwin anastomoses, associated with subchorionic fibrin deposition. Microscopically, laser-treated vessels showed varying degrees of necrosis, associated with focal hemorrhage, avascular villi, and fibrin deposition in the underlying parenchyma. In some cases of intrauterine fetal demise or placental disruption, no definite laser scars were identified. As expected, the number of residual anastomoses (all types) was significantly smaller in laser-treated placentas than in control monochorionic placentas (2.4 +/- 2.2 [ n = 10] vs. 6.2 +/- 3.2 [ n = 70], P < 0.01). Velamentous cord insertion was noted in 50% of cases; markedly uneven placental sharing in 60%. Detailed analysis of laser-treated placentas and clinicopathological correlation may lead to a better understanding of the pathophysiology of TTTS and continued refinement of therapeutic approaches for this often lethal condition.