Endometrioid-like variant of ovarian yolk sac tumor with foci of carcinoid: an ultrastructural study

Yolk Sac Tumor of the Ovary: A Report of 150 Cases and Review of the Literature

One hundred fifty yolk sac tumors (YSTs) of the ovary in patients from 1 to 61 (mean: 21.5) years of age are described; 75% of the patients were in the second and third decades and only 1 was above 50 years of age. The clinical manifestations were typically related to a fast-growing adnexal mass; endocrine manifestations (hirsutism) were present in only 2 cases. The tumors were all unilateral and 70% were ≥15 cm; an associated dermoid cyst was present in 20 cases. The tumors were solid and cystic in 57% of the cases, 25% were multicystic, and 18% uniformly solid. The solid tissue was typically tan to pink or yellow and often friable with hemorrhage and necrosis; smaller solid neoplasms were sometime uniformly yellow. The most common histologic pattern was reticular composed of an irregular meshwork of spaces that was conspicuous in 68% of the neoplasms but present to at least a minor degree in all of them. That appearance almost always merged with small to large cysts that were prominent in about 40% of tumors. In 25% of the tumors, cysts sometimes associated with a cellular stroma (the polyvesicular pattern), were present but conspicuous in only half these cases. One third of the tumors had a labyrinthine pattern, 22% glands, and 6% a festoon pattern. Papillae with a central blood vessel (Schiller-Duval bodies) were seen in one-third of the tumors but were numerous in only 5% of them. Nonspecific appearing papillae were seen in 10% of the tumors. A solid growth of cells with pale cytoplasm was seen in one-third of the tumors but was conspicuous in only half of that subset. The solid appearance was typically reminiscent of that of dysgerminoma, but lacked the septa and lymphocytic infiltrate of that neoplasm. Nine tumors had a component of cells with scant cytoplasm resulting in a blastema-like appearance and 3 had cells with abundant clear cytoplasm. Cords and clusters of cells were common but did not dominate the microscopic appearance. The stroma typically had a nonspecific collagenous to edematous appearance. Stromal luteinization was seen in 12 tumors; in 5 this was likely due to the patient being pregnant. Two tumors had minor foci of cells that resembled hepatocytes. Hyaline bodies were seen in most of the tumors and were often conspicuous. The neoplastic cells typically had modest amounts of lightly staining cytoplasm and only mild nuclear pleomorphism. Cells lining cysts were often flattened sometimes resulting in a deceptively innocuous appearance. Many of the tumors (mostly consultation cases), caused diagnostic difficulty; tumors in the differential diagnosis included clear cell carcinoma, embryonal carcinoma, Sertoli-Leydig cell tumor, and juvenile granulosa cell tumor. The patient age and marked elevation of the serum alpha-fetoprotein level (if measured) is helpful in many of these considerations. The overtly malignant gross appearance of most YSTs contrasts with certain other tumors in the differential and the association of some YSTs with dermoid cyst and many clear cell carcinomas with endometriosis may be helpful. The vast majority of ovarian YSTs are dominated microscopically by merging of reticular and cystic patterns which, although focally mimicked by other neoplasms, are in general characteristic, and distinctive features of other neoplasms are absent. Immunohistochemistry, particularly for alpha-fetoprotein and glypican 3, and lack of staining for various markers of other neoplasms is helpful but overlap exists and these results must be considered in the context of the overall clinical, gross, and microscopic features. YSTs dominated by hepatoid and glandular features are rare and their categorization as YSTs should be done cautiously if thoroughly sampled tumors show no evidence of classic features of YST emphasized herein and first elaborated by the Danish investigator Gunnar Teilum whose seminal observations have stood the test of time.

Yolk sac tumours of the female genital tract in older adults derive commonly from somatic epithelial neoplasms: somatically derived yolk sac tumours

AIMS

To report 18 yolk sac tumours (YSTs) of the female genital tract (17 ovary, one uterus) in patients aged 40 years or over, most arising from a somatic epithelial neoplasm.

METHODS AND RESULTS

Six patients had pure YST, two were associated with immature teratoma (one with an endometrioid adenocarcinoma) and in 11 there was an epithelial neoplasm comprising high-grade serous carcinoma (HGSC) (n = 5), clear cell carcinoma (n = 1), borderline clear cell adenofibroma (n = 1), endometrioid adenocarcinoma (n = 2), serous tubal intra-epithelial carcinoma (n = 1) and large-cell neuroendocrine carcinoma (n = 1). In one case of pure YST, there was an ipsilateral endometriotic cyst but no other neoplastic component. In two cases, the YST was a hepatoid variant and in most of the others it exhibited predominantly glandular morphology, closely mimicking an epithelial neoplasm.

CONCLUSIONS

Pathologists should be aware of the association between YST and an epithelial neoplasm, the former probably arising from the latter through a process of neometaplasia/retrodifferentiation. Those rare gynaecological pure glandular YSTs in adults may arise secondary to total overgrowth of an epithelial neoplasm. Pathologists need a high index of suspicion to diagnose the YST component, as the morphology is characteristically of a glandular variant with marked morphological overlap with adenocarcinomas. There is also often significant immunophenotypical overlap with epithelial neoplasms, as the YST component may be positive with epithelial membrane antigen (EMA), BerEP4 and cytokeratin 7 (CK7), as well as YST markers. We propose the term 'somatically derived YSTs' for these neoplasms and suggest unification of the terminology between different sites where such neoplasms occur.

Recent Advances in the Pathology and Classification of Ovarian Germ Cell Tumors

In recent years, our knowledge of ovarian germ cell tumors has increased, and their classification has evolved. The introduction of cisplatin-based chemotherapy and the discovery of tumor markers, including alpha-fetoprotein and human chorionic gonadotropin, have dramatically changed the clinical outlook for most of these patients. In this review, recent advances in the classification and pathology of ovarian germ cell tumors are discussed. Where appropriate, comparisons are made with testicular germ cell tumors. The last section of the article discusses the pathogenesis of germ cell tumors. This review will emphasize the articles written in the last 10 years and those that have significantly advanced our knowledge of germ cell tumors in past decades.

Mucinous Carcinoid as an Unusual Manifestation of Endodermal Differentiation in Ovarian Yolk Sac Tumors

We present, for the first time, two yolk sac tumors (YST) in women 37 and 18 years of age, one with a typical parietovisceral pattern and the other with a glandular pattern, which were associated with extensive areas of mucinous carcinoid (MC). The tumor in the first case had numerous nodules of tubulopapillary YST that merged with well-differentiated MC. This patient responded well to chemotherapy. The tumor in the second case consisted of an AFP-positive glandular YST, with a glandulopapillary pattern closely resembling fetal lung type adenocarcinoma, coexisting with an AFP-negative, cytokeratin 20-positive, atypical MC; transitional areas between the two components were also seen. In the material from the recurrences and metastases; however, no YST was present, the atypical MC having become the predominant component including areas that had become carcinomatous. There was a poor response to various chemotherapeutic regimens. AFP levels became negative during the course of disease paralleling the disappearance of the YST component and the overgrowth of an increasingly anaplastic MC. The patient died 1 year after diagnosis. We think that, in these cases, MC represented an unusual form of endodermal differentiation of the YST. It is important to differentiate the yolk sac and carcinoid components due to their different responses to chemotherapy and to evaluate the possibility of mucinous carcinoid developing into a highly aggressive carcinoma.

The role of electron microscopy in gynecological pathology

Electron microscopy, as a diagnostic method, has been available to pathologists for about half a century. Its use in studying normal and abnormal gynecological tissues has been applied during the second half of that period, and many works on specific female genital topics have been published. Several of those subjects are worthy of citing in a review of the present type. Clear cell carcinoma has been revealed to be a mullerian, rather than a wolffian, derivative. Small cell carcinoma of the ovary with hypercalcemia is comprised of cells shown ultrastructurally to be epithelial, but unlike surface epithelial cells, germ cells, sex-cord cells, or neuroendocrine cells. Further electron microscopic studies provided evidence that these small cell tumors are not adult diffuse granulosa cell tumors, endometrioid stromal tumors, primitive neuroectodermal tumors, or numerous other primary and metastatic small cell tumors. Electron microscopy has also been useful in determining that not all signet-ring cell tumors of the ovary are stromal, and that there are multiple types of signet-ring (vacuolated) cells in ovarian tumors. Smooth muscle tumors are well known to have multiple light microscopic phenotypes, and electron microscopy has proven to be diagnostic in many of these cases, especially in epithelioid smooth muscle tumors. A number of other gynecological neoplasms that have been better defined by electron microscopic studies are described. Embryology and histogenesis are other areas of study in which electron microscopy has been a major contributor of new information at the subcellular level. Electron microscopy, solely or in harmony with clinical information, light microscopy, and immunohistochemistry, has been and is a valuable tool for the pathologist in the study of histogenesis and accurate diagnosis of gynecological lesions.

Ovarian yolk sac tumor with endometrioid carcinoma arising from endometriosis in a postmenopausal woman, with special reference to expression of alpha-fetoprotein, sex steroid receptors, and p53

A case of a yolk sac tumor (YST) with an ovarian endometrioid adenocarcinoma arising from endometriosis in a postmenopausal woman is described. Clinically, the case showed an aggressive course and did not respond to chemotherapy; the patient died of her disease 6 months after the operation. Histologically, the tumor consisted predominantly of an endometrioid adenocarcinoma, but it also showed microscopic features characteristic of YST. The tumor also contained benign endometriotic lesions with direct transition to the endometrioid adenocarcinoma. Immunohistochemical study revealed that not only the YST, but also the endometrioid adenocarcinoma was partly positive for alpha-fetoprotein. There was an inverse relationship between the endometriosis and the endometrioid adenocarcinoma in terms of the expression of sex steroid receptors and p53: adenocarcinoma cells were positive for p53 but negative for sex steroid receptors, whereas endometriotic epithelial cells were positive for sex steroid receptors but negative for p53.