Other Germ Cell Tumors

Slide 1 · Other Germ Cell Tumors

Ovarian embryonal carcinoma · polyembryoma · mixed germ cell tumors

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Define the three entities grouped under “other germ cell tumors”.

Use differentiation patterns to recognize the constituents of mixed ovarian tumors.

Contrast embryonal carcinoma with dysgerminoma and extraembryonic elements.

Apply morphology and markers without overinterpreting source-limited findings.

Slide 3 · The scope of “other germ cell tumors”

Entity

Core definition

Key diagnostic idea

Embryonal carcinoma

Malignant primitive embryonal neoplasm

Morphologically similar to testicular embryonal carcinoma

Polyembryoma

Malignant tumor containing embryoid bodies

An uncommon embryoid pattern

Mixed germ cell tumor

Combination of more than one germ-cell subtype

Identify each constituent independently

Slide 4 · Location within ovarian tumor taxonomy

Ovarian germ cell tumors are a distinct family from epithelial and sex cord–stromal tumors.

The germ-cell family includes mature and immature teratomas, dysgerminoma, yolk sac tumor, choriocarcinoma and rarer types.

The “other” heading encompasses uncommon pure neoplasms and tumors with multiple germ-cell components.

Slide 5 · Differentiation explains the ovarian germ-cell spectrum

Teaching schematic: Classification follows the line of differentiation expressed by tumor cells.

Primitive germ cell

Common neoplastic cell of origin

Lineage direction

Gonadal / embryonic / extraembryonic

Recognizable tissue

Dysgerminoma / teratoma / yolk sac / trophoblast

Slide 6 · Major ovarian germ-cell differentiation patterns

Pattern

Tumor

Recognizable hallmark

Germ-cell / oogonial

Dysgerminoma

Primitive uniform cells; lymphocyte-rich septa

Embryonic tissue

Teratoma

Mature or immature tissue derivatives

Yolk-sac lineage

Yolk sac tumor

Schiller–Duval body; AFP-associated droplets

Placental lineage

Choriocarcinoma

Trophoblast; hCG production

Primitive embryonal

Embryonal carcinoma

Markedly atypical embryonal-type epithelium

Slide 7 · How common are ovarian germ-cell tumors?

As a family they account for approximately 15%–20% of ovarian tumors.

Most are benign mature cystic teratomas in patients of reproductive age.

The less common malignant germ-cell neoplasms become particularly relevant in children and younger adults.

These background proportions do not describe the frequency of embryonal carcinoma or polyembryoma individually.

Slide 8 · Pure and mixed describe composition

Pure germ-cell tumor

One histologically recognized germ-cell tumor type is identified.

The designation does not by itself specify stage or prognosis.

Mixed germ-cell tumor

Two or more distinct germ-cell histologies coexist.

Each component must be described; One component should not be assumed to represent the entire mass.

Slide 9 · A conceptual map of a mixed tumor

Dysgerminoma

Teratoma

Yolk sac

Choriocarcinoma

Interpretation

Different histologic regions can coexist in one ovarian mass.

The schematic does not represent a patient specimen.

Each region requires its own morphologic interpretation.

Slide 10 · Three questions to ask at initial review

Is the neoplasm composed of one histologic population or multiple populations?

If primitive cells are present, do their cytologic and architectural features resemble embryonal carcinoma or dysgerminoma?

Do differentiated areas support yolk-sac, trophoblastic, or teratomatous elements?

Can every proposed component be supported by histology and appropriate ancillary findings?

Slide 11 · Embryonal carcinoma: Definition

A highly malignant germ-cell neoplasm composed of primitive embryonal elements.

The ovarian form is as histologically similar to testicular embryonal carcinoma.

The detailed features below are drawn from that testicular morphologic comparator—not from an ovarian outcome series.

Slide 12 · Primitive embryonal versus oogonial differentiation

Embryonal carcinoma

Primitive epithelial-like cells with substantial nuclear atypia.

Architectural patterns can include tubules, alveoli, papillae and sheets.

Dysgerminoma

More uniform large cells with clear cytoplasm and recognizable borders.

Fibrous septa are commonly populated by lymphocytes.

Slide 13 · Embryonal carcinoma: Architectural vocabulary

Tubular

Schematic

Alveolar / cleft-like

Schematic

Solid

Schematic

Interpretation

Alveolar or tubular arrangements may be present.

Papillary folding and solid areas may occur.

Original pattern schematic; Not H&E evidence.

Slide 14 · Embryonal carcinoma: Cytologic profile

Large epithelial-appearing cells show pronounced anaplasia.

Nuclei are hyperchromatic, with multiple prominent nucleoli.

Cell and nuclear sizes and shapes vary considerably (pleomorphism).

Cell borders are commonly indistinct, unlike the crisp borders in typical dysgerminoma.

Slide 15 · Atypia and cellular turnover

The comparator frequently contains mitotic figures.

Tumor giant cells may accompany the high-grade epithelial-like component.

Necrosis and hemorrhage can accompany aggressive tumor growth.

These changes support concern but do not independently establish an ovarian subtype.

Slide 16 · Embryonal morphology: Architecture and cytology

Architectural clues

Alveolar and tubular patterns

Papillary folds

Solid sheets with cleft-like spaces

Cytologic clues

Large anaplastic epithelial cells

Hyperchromasia and prominent nucleoli

Pleomorphism; Indistinct borders; Mitoses

Slide 17 · Gross examination: Comparator evidence

Testicular embryonal carcinoma is often variegated on sectioning because of necrosis and hemorrhage.

Robbins does not provide a separate gross specification for ovarian embryonal carcinoma in this heading.

In an ovarian mixed tumor, gross heterogeneity is a reason to correlate distinct regions with microscopy—not proof of any one lineage.

Slide 18 · IHC patterns in the Robbins testicular comparator

Marker

Embryonal carcinoma

Seminoma comparator

OCT3/4

Typically positive

Typically positive

SALL4

Typically positive

Not specified here in this contrast

Cytokeratin

Typically positive

Typically negative

KIT

Typically negative

Typically positive

Podoplanin

Typically negative

Typically positive

Slide 19 · How to transfer comparator IHC cautiously

The positive and negative stain patterns on the preceding slide are stated for testicular tumors.

Ovarian dysgerminoma is independently described as expressing OCT3, OCT4, NANOG and KIT.

The ovarian embryonal carcinoma paragraph itself gives no standalone sensitivity estimates or required panel.

Use this cross-gonadal comparison as a teaching clue, not an unqualified ovarian diagnostic rule.

Slide 20 · Primitive ovarian germ-cell differential

Feature

Embryonal carcinoma*

Dysgerminoma

Nuclear morphology

Marked pleomorphism; prominent nucleoli

More uniform, central regular nuclei

Cell borders

Often indistinct

Well defined

Growth pattern

Alveolar / tubular / sheets

Sheets or cords with fibrous septa

Inflammation

No defining septal feature given

Lymphocyte-rich stroma common

Reference caveat

*Morphology from testicular analogue

Ovarian description in Ch. 22

Slide 21 · Do not diagnose from “primitive” appearance alone

A primitive-looking ovarian germ-cell tumor is not automatically embryonal carcinoma.

Evaluate epithelial-like architecture, pleomorphism, cell borders and septal lymphocytes together.

Consider whether a sample is part of a heterogeneous, mixed neoplasm.

If morphology and markers conflict, revisit sampling and interpretation before committing to a lineage.

Slide 22 · What the source establishes about behavior

Robbins explicitly calls ovarian embryonal carcinoma highly malignant.

The ovarian subsection provides neither an isolated stage-specific survival estimate nor a distinctive molecular driver.

The testicular comparator is described as more aggressive than seminoma and commonly showing vascular–lymphatic invasion.

Do not transpose numerical prognostic estimates from testis to ovary.

Slide 23 · Polyembryoma: The essential identity

Polyembryoma as a malignant ovarian germ-cell tumor.

Its defining descriptive feature is the presence of embryoid bodies.

The source does not supply detailed ovarian gross findings, an IHC signature or outcome rates for this entity.

Slide 24 · Embryoid bodies: Simplified concept

Abstract embryoid forms

NOT diagnostic histology

Interpretation

The central teaching term is “embryoid body.”

Arrangement is deliberately stylized, not a validated microscopic image.

Recognizing the rare entity requires actual histologic assessment.

Slide 25 · Polyembryoma and embryonal carcinoma are distinct labels

Embryonal carcinoma

Defined as a highly malignant tumor of primitive embryonal elements.

Robbins supplies a testicular histologic analogue with cytologic detail.

Polyembryoma

Defined by embryoid bodies in an ovarian germ-cell malignancy.

The supplied passage gives no equivalent detailed morphologic or marker profile.

Slide 26 · Polyembryoma: Evidence-based diagnostic restraint

The presence of the word “embryoid” does not make polyembryoma synonymous with embryonal carcinoma.

The descriptive source is too limited to build a validated multi-feature diagnostic algorithm for polyembryoma.

A pattern suggestive of embryoid bodies should prompt precise morphology review, not an invented immunostain rule.

No specific prevalence or survival percentage is provided here.

Slide 27 · Why rare categories matter in mixed tumors

A rare ovarian germ-cell phenotype may be focal rather than the dominant gross appearance.

The label must correspond to demonstrable tissue architecture, not merely a broad “primitive germ-cell” impression.

A mixed diagnosis is more informative when individual tumor components are explicitly identified.

These are diagnostic-reasoning principles; The source does not prescribe a sampling count.

Slide 28 · Mixed germ-cell tumor: Source definition

A tumor containing more than one distinct germ-cell tumor type.

Dysgerminoma, teratoma, yolk sac tumor and choriocarcinoma as possible components.

“Mixed” communicates histologic composition; It is not synonymous with a specific marker pattern.

Slide 29 · Four components explicitly listed

Component

Differentiation

Signature to seek

Dysgerminoma

Germ-cell/oogonial

Uniform clear cells; lymphocyte-rich fibrous septa

Teratoma

Somatic tissue differentiation

Mature or immature tissues; immature neuroepithelium

Yolk sac tumor

Extraembryonic yolk sac

Schiller–Duval bodies; AFP-associated globules

Choriocarcinoma

Trophoblastic / placental

Cytotrophoblast + syncytiotrophoblast; hCG

Slide 30 · Mixed tumor: From gross regions to component diagnosis

Schematic diagnostic workflow; The source gives no mandatory block count.

Sample diverse areas

Represent morphologically different regions

Identify each pattern

Apply lineage-defining morphology

Correlate findings

Use selective marker / clinical context

Describe mixture

Record recognized constituents

Slide 31 · Why heterogeneity creates sampling risk

A solid and pale region may not have the same histology as a hemorrhagic or cystic region.

Dysgerminoma is often soft and fleshy; Teratomas may contain recognizable differentiated tissues.

Embryonal or trophoblastic elements may coexist in a tumor with another dominant pattern.

Thus a small selected sample may not capture the complete histologic mixture.

Slide 32 · Morphology-directed tissue evaluation

Pale, solid area

Consider dysgerminoma-type architecture.

Check for uniform cells and lymphocytic septa.

Cystic / tissue-rich area

Look for differentiated tissue types.

Determine whether immature neuroepithelium is present.

Hemorrhagic / variegated area

Review for primitive or trophoblastic elements.

Do not classify from gross color alone.

Slide 33 · Dysgerminoma: Recognizable histology

Sheets or cords of large vesicular cells with clear cytoplasm and distinct boundaries.

Nuclei are centrally located and relatively regular.

Scant fibrous septa are infiltrated by lymphocytes; Granulomas may also occur.

Dysgerminoma as the ovarian counterpart of testicular seminoma.

Slide 34 · Dysgerminoma architecture: Schematic

Large tumor cells

Lymphocytes in septum

Interpretation

Large tumor cells arranged in lobules or sheets.

Lymphocytes are concentrated within intervening fibrous septa.

Native drawing; Not a photomicrograph.

Slide 35 · Dysgerminoma: Lineage-related markers

The pluripotency-associated transcription factors OCT3, OCT4 and NANOG.

Expression of KIT is a notable characteristic; The book discusses activating KIT alterations.

These findings provide context when separating dysgerminoma from other primitive germ-cell patterns.

The histologic distribution and architectural pattern remain indispensable.

Slide 36 · Yolk sac tumor: Extraembryonic lineage

A malignant ovarian germ-cell tumor showing yolk-sac differentiation.

The tumor produces α-fetoprotein (AFP), also found in intracellular or extracellular hyaline globules.

A Schiller–Duval body is a recognizable glomerulus-like architectural clue.

Yolk sac tumor may represent one constituent of a mixed ovarian neoplasm.

Slide 37 · Schiller–Duval body: Native schematic

Central capillary

Tumor-cell cuff

Lined space

Interpretation

A central capillary lies within a projection of tumor cells.

A surrounding space is lined by additional tumor cells.

The complete architecture resembles a primitive glomerulus.

Slide 38 · Yolk sac tumor: Morphology beyond one structure

Schiller–Duval bodies are characteristic, but assessment must not rely on their presence in every section.

Hyaline globules can occur within and outside the tumor cells.

In the Robbins male-gonadal comparator, reticular and papillary patterns also occur.

Use these analogies cautiously when reviewing ovarian mixed tumor morphology.

Slide 39 · Choriocarcinoma: An extraembryonic component

Ovarian choriocarcinoma exhibits trophoblastic differentiation analogous to the placenta.

Most ovarian lesions coexist with another germ-cell tumor; Pure lesions are extremely rare.

These tumors elaborate chorionic gonadotropins and can disseminate hematogenously.

The source contrasts their unfavorable therapy response with gestational choriocarcinoma.

Slide 40 · Choriocarcinoma: Two trophoblastic cell types

Cytotrophoblast

More regular mononuclear cells.

Polygonal with distinct borders and relatively clear cytoplasm.

Syncytiotrophoblast

Large multinucleated cells with eosinophilic, vacuolated cytoplasm.

Contains hCG detectable with immunohistochemistry.

Slide 41 · Teratomatous components: Maturity matters

Mature cystic teratomas commonly contain skin with adnexal structures and multiple differentiated tissue types.

Immature teratomas include embryonal or fetal-type tissue, especially primitive neuroepithelium.

The histologic grade of ovarian immature teratoma is based on the amount of immature neuroepithelium.

Mature and immature elements must not be conflated in a mixed tumor description.

Slide 42 · How components differ morphologically

Histology

Architecture

Additional clue

Dysgerminoma

Uniform sheets / cords

Fibrous septa with lymphocytes

Embryonal carcinoma*

Tubules / alveoli / papillae / sheets

Pleomorphic high-grade nuclei

Yolk sac tumor

Glomeruloid and variable patterns

AFP-associated hyaline globules

Choriocarcinoma*

Cytotrophoblast with syncytiotrophoblast

Hemorrhage; hCG production

Teratoma

Diverse somatic tissues

Neuroepithelial immaturity when present

Slide 43 · Interpret serum products by component

Product

Relevant component

Interpretive limitation

AFP

Yolk sac differentiation

Marker supports a component, not the full mixture

hCG

Trophoblastic differentiation

Dysgerminoma may also have syncytiotrophoblasts

No single elevation

Possible diverse components

Cannot exclude mixed germ-cell histology

Slide 44 · A shared marker does not establish one diagnosis

OCT3/4 positivity

Staining in embryonal carcinoma (testicular comparator).

The ovarian dysgerminoma section also identifies OCT3/OCT4 expression.

Resolve with pattern

Assess cell borders, cytologic atypia and septal architecture.

For the embryonal comparator, cytokeratin/KIT profiles add differential context.

Slide 45 · Morphology and lineage evidence must agree

Candidate

Positive morphologic support

Helpful corroboration

Dysgerminoma

Uniform clear cells; lymphocyte-rich septa

OCT3/4 and KIT

Yolk sac tumor

Schiller–Duval body; hyaline globules

AFP production / staining

Choriocarcinoma

Two trophoblastic cell types

hCG production

Immature teratoma

Immature neuroepithelium

Amount of immature tissue relates to grade

Embryonal carcinoma

High-grade primitive epithelium*

Comparator: OCT3/4, SALL4, CK positivity

Slide 46 · A disciplined classification sequence

Teaching workflow built from the Robbins descriptions; Not an official diagnostic protocol.

Recognize a germ-cell pattern

Exclude unrelated lineage morphologically

Identify differentiated elements

Look for multiple distinct patterns

Correlate markers

Use AFP / hCG / immunophenotype judiciously

Name every component

Pure vs mixed + specified constituents

Slide 47 · Reporting a mixed ovarian germ-cell tumor

Name the constituent germ-cell tumor types supported by histology.

Document any mature or immature teratomatous differentiation distinctly.

Communicate relevant malignant elements rather than labeling the tumor generically as “germ-cell.”

The supplied pages do not specify a required proportion cutoff for labeling a mixed component.

Slide 48 · What a mixed diagnosis communicates—and what it does not

It communicates

More than one neoplastic germ-cell differentiation pattern.

The identity of recognized constituent tumor types.

A rationale for examining heterogeneity.

It does not automatically convey

A uniform serum AFP or hCG level.

One fixed prognosis for all possible mixtures.

A single predetermined chemotherapy protocol.

Slide 49 · Behavior varies across ovarian germ-cell subtypes

Pure mature cystic teratoma is generally benign, although malignant transformation can occur rarely.

Dysgerminoma is malignant but can be highly responsive to chemotherapy.

Yolk sac tumor is malignant, and the Robbins text links outcome to stage under combination chemotherapy.

Ovarian choriocarcinoma is described as aggressive; Do not generalize its course to every mixed tumor.

Slide 50 · Stage, grade and histologic type are different variables

Stage addresses how far a neoplasm has spread, not which germ-cell lineage it resembles.

Ovarian immature teratoma grade is tied to the proportion of immature neuroepithelium.

Mixed histology describes component identity; It is not interchangeable with immature teratoma grade.

Avoid assigning unprovided survival estimates to embryonal carcinoma, polyembryoma or uncharacterized mixtures.

Slide 51 · Case application 1: Primitive solid tumor

Illustrative case (hypothetical)

An ovarian mass in a young adult contains broad sheets of large tumor cells. Cells have clear cytoplasm and sharply outlined membranes; Lymphocytes occur in fibrous septa.

Discussion

Which ovarian germ-cell tumor has this defining pattern?

What morphologic findings oppose the embryonal carcinoma comparator?

Slide 52 · Case 1: Diagnostic justification

Dysgerminoma has regular centrally situated nuclei and clear, well-demarcated cytoplasm.

Its stroma commonly consists of fibrous septa with lymphocytes.

Embryonal carcinoma’s testicular analogue has indistinct borders and greater pleomorphism.

A marker panel is interpreted after—not instead of—these architectural observations.

Slide 53 · Case application 2: Focal glomeruloid structure

Illustrative case (hypothetical)

A partly heterogeneous ovarian germ-cell mass contains a microscopic focus with a central capillary surrounded by tumor cells inside a space lined by tumor cells. Hyaline droplets are also present.

Discussion

What specific germ-cell component should be identified?

Which tumor product supports this lineage?

Slide 54 · Case 2: A component can be focal

The described architecture is a Schiller–Duval body, characteristic of yolk sac differentiation.

Hyaline droplets provide a second morphologic clue.

AFP is associated with yolk sac tumor cells, but its presence does not define every part of a heterogeneous tumor.

Other regions must be characterized before deciding whether the final diagnosis is pure or mixed.

Slide 55 · Case application 3: Trophoblastic focus

Illustrative case (hypothetical)

An ovarian germ-cell tumor contains an area with mononuclear cells intermingled with large multinucleated eosinophilic cells; The clinical record notes raised chorionic gonadotropin.

Discussion

Which differentiated component is suggested?

Why must the remaining mass still be examined?

Slide 56 · Case 3: HCG does not identify the whole tumor

Choriocarcinoma has intimately mixed cytotrophoblast and syncytiotrophoblast.

The syncytiotrophoblastic component is associated with hCG production.

Some dysgerminomas also contain syncytiotrophoblastic giant cells and may elevate hCG.

Therefore both the morphology of the focus and the remainder of the specimen matter.

Slide 57 · Case application 4: Embryoid architecture

Illustrative case (hypothetical)

A rare ovarian germ-cell malignancy is described in a pathology consultation as containing embryoid bodies. No detailed immunophenotype is supplied in the assigned textbook section.

Discussion

Which uncommon named entity is present in the Robbins differential?

What additional claims should not be made from this source alone?

Slide 58 · Case 4: Limits of a one-sentence entity definition

Polyembryoma is classified as malignant in the assigned Robbins passage.

Embryoid bodies are the stated defining morphologic feature.

Additional detailed criteria and modern taxonomic distinctions require a separately identified, verified source.

Restrained diagnosis is preferable to a falsely precise description.

Slide 59 · Contrast: Mature and immature teratomatous tissue

Mature teratoma

Differentiated skin, glandular, cartilage, bone, neural or thyroid elements may be present.

Mature cystic teratomas are usually benign.

Immature teratoma

Embryonal / fetal-type elements, notably primitive neuroepithelium.

Proportion of immature neuroepithelium is used for grade.

Slide 60 · Synthesis: Five discriminating observations

Uniform clear cells and inflammatory septa point toward dysgerminoma.

Markedly atypical primitive epithelial patterns favor the embryonal comparator.

A glomeruloid Schiller–Duval body points to yolk sac differentiation.

Biphasic trophoblast and hCG support choriocarcinomatous differentiation.

Mixed tumors require explicit accounting of multiple components.

Slide 61 · Source-limited facts versus reasoned application

Directly stated in Robbins

Reasoned diagnostic application

Embryonal carcinoma is highly malignant

Seek aggressive primitive epithelial morphology

Polyembryoma contains embryoid bodies

Avoid inventing absent subtype-specific criteria

Mixed tumors contain varied germ-cell types

Examine heterogeneous regions for components

AFP / hCG associate with specific lineages

Do not let one serum marker define the whole mass

Slide 62 · End-of-lecture diagnostic synthesis

The “other germ cell tumor” grouping contains two uncommon named primitive tumors and mixed neoplasms.

Mixed histology is determined by identifying the individual germ-cell components—not by serum products alone.

Embryonal carcinoma, polyembryoma and germ-cell lineages must be distinguished morphologically.

Interpret testicular analogies and unquantified ovarian findings with appropriate source caveats.

Slide 63 · Primary reference and evidence boundaries

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th ed. (2026), Chapter 22, pp. 929–931.

Additional morphologic comparator: Chapter 21, “Embryonal Carcinoma,” pp. 883–884.

Ovarian entity definitions were prioritized; specific comparator facts are flagged where applicable.

Conceptual native schematics are not actual microscopic or gross images.