Context.—The field of ovarian germ cell tumors (OGCTs) has remained relatively unchanged in the last 2 decades. However, the introduction of new stem cell pluripotency markers has provided a new understanding into the identification and taxonomy of OGCT types. New data have provided new insights into unusual teratoma-associated autoimmune disorders and the origin of gliomatosis peritonei. Objective.—To review the impact of new pluripotency markers in the diagnosis of malignant OGCT (MOGCT) and analyze new nomenclature proposals and clinicopathologic entities. Data Sources.—Ovarian germ cell tumors from routine material and expert consultation files at San Cecilio University Hospital, Granada, Spain, and the relevant literature were reviewed. Conclusions.—Although a correct diagnosis of MOGCT can often be made with histologic and classic immunohistochemical studies, the new immunohistochemical pluripotency markers give higher diagnostic accuracy. Germ cell tumors represent a caricature of the phases of normal embryonic differentiation from primordial germ and stem cells to extraembryonal and somatic tissue differentiation. Since every stage of differentiation and its related tumor type exhibit characteristic markers, the analysis of their expression facilitates tumor typing, thus complementing the use of classic antibodies. They also allow a more precise evaluation of the degree of immaturity in teratoma. The new term, primitive endodermal tumors, simplifies the understanding of the complex histology of the yolk sac tumor group, as this terminology encompasses its multiple endodermal differentiations. Recently described autoimmune encephalitis due to antibodies against the N-methyl-d-aspartate receptor has become the most frequent autoimmune disorder associated with ovarian teratoma.

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.

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Gliomatosis peritonei (GP) is an unusual condition in which nodules of mature astroglia, often miliary and microscopic in size, are widespread in the peritoneum and abdominal lymph nodes. Its behaviour is benign and it is usually found in association with ovarian teratoma and rarely with teratomas of other organs. Implants grow rapidly and can remain unchanged for life. Astroglia is the main component, but other neural lineage elements and many other tissues can be found. Cells are mature but not terminal, since they express SOX2. Secondary associated lesions include: a) degenerative astrocytic changes, b) granulomatous and follicular chronic inflammatory changes, c) association with hormonally related changes, such as decidual peritoneal metaplasia and endometriosis and d) endothelial and adventitial vascular hyperplasia leading to haemoperitoneum. Two pathogenetic mechanisms are considered: direct seeding of immature neural cells from a primary tumour with subsequent differentiation and metaplasia from peritoneal stem cells. The former proposal is supported by clinicopathologic data such as ample cellular heterogeneity, coexistence of mature astroglia with neural blastema, as well as the shed keratin and hairs from the ovarian neoplasm. However, metaplasia is sustained by a heterozygosity pattern of GP nodules, identical to the normal tissue and different from the coexistent ovarian teratoma. GP would constitute a response to growth factors from teratoma or macrophages. While an implantative origin from ovarian teratoma remains in most cases a more probable mechanism, metaplasia from peritoneal stem cells would explain cases of GP which present a monomorphic astrocytic cell population.

HighlightsCervical Müllerian adenosarcomas with sarcomatous overgrowth are rare and aggressive.Recurrence is more likely when less radical surgery is performed.Radiotherapy and ifosfamide and platinum chemotherapy may aid disease control.