Grade / Category

Histological Features (Mucious Tumors)

Note

Grade 0

(Low Malignant Potential (LMP))

Complex glandular pattern with no stromal invasion. Up to three layers of cells with mild to moderate atypia may be observed. No severe atypia, solid areas, papillary tufting, or cribriform.

Grade 1

(Well Differentiated Carcinoma)

Either stromal invasion indicated by a desmoplastic host response, or epithelial stratification of 4 or more cell layers. Solid growth is <5%.

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Grade 2

(Moderately Differentiated Carcinoma)

More complex glands or smaller glands are present with an increase in the degree of nuclear atypia. Stratification is greater and invasion is generally present. Solid areas are > % and <50%.

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Grade 3

(Poorly Differentiated Carcinoma)

Marked nuclear atypia, pleomorphism, and multinucleated cells are characteristic. The glands are poorly formed and large sheets of tumor without glands or stroma are present (greater than 50% is solid). Mucin secretion may be lost in a majority of the cells, or seen only with special stains.

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Grade / Category

Histological Features (Serous Tumors)

Note

Grade 0

(Low Malignant Potential (LMP))

These are serous tumors with no stromal invasion characterized by branching papillae having fibrous cores. Cellular stratification is present with several cell layers piled on top of each other. Cellular budding or tufting, may appear as detached clusters at the end of papillae. Cytologic atypia and mitotic activity are present.

Grade 1

(Well Differentiated Carcinoma)

A serous carcinoma must have definite invasion of stroma. Well-formed papillary processes and glands, minimal disorientation of nuclei with only mild stratification, minimal nuclear pleomorphism and hyperchromatism are characteristic. Less than 5% solid areas are present. If invasive focus is less than 3 mm, this should be noted.

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Grade 2

(Moderately Differentiated Carcinoma)

This tumor forms more complex papillary and glandular structures with more pronounced nuclear atypia. Small areas of solid tumor growth may be seen (greater than 5% but less than 50%)

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Grade 3

(Poorly Differentiated Carcinoma)

This tumor is still recognizable as serous but contains large areas of solid growth (more than 50%) with marked pleomorphism, nuclear hyperchromasia, and giant cell formation

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Grade / Category

Histological Features (Endometrioid Carcinoma)

Note

Grade 1

(Well Differentiated Carcinoma)

Tumor resembles the typical villoglandular carcinoma of the uterine corpus. The glands are well-formed. Less than 5% of the tumor is solid. Squamous differentiation may be present.

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Grade 2

(Moderately Differentiated Carcinoma)

The glands present are more complex with increased stratification. Occasional small solid nests of tumor are seen, but constitute a component greater than 5% but less than 50% of the tumor. Squamous differentiation may be present.

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Grade 3

(Poorly Differentiated Carcinoma)

This tumor has poorly formed glands, nests, and large sheets of cells with greater than 50% of the tumor solid. Squamous differentiation may be present.

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Grade / Category

Histological Features (Ovarian Teratomas)

Note

Grade 0

All components are mature and mitotic activity is rare or absent. Well sampled grade 0 primary teratomas are regarded as benign.

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Grade 1

Some immature elements of any origin. Immature neural tissue or neuroepithelium is rare (i.e. <1 HPF). Mitotic activity is low. An aggregate area of one low-power microscopic field (4xobj and 10x eyepiece) exceeds the minor amount of immature brain or neuroepithelium.

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Grade 2

Immature element of any origin and immature neural element(s) are present to a greater degree than grade 1. Immature neural tissue or neuroepithelium is more common than grade 1 but does not exceed an aggregate area of 3 low-power microscopic fields (4x objective) in any one slide. Mitotic activity is moderate.

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Grade 3

Prominent immature element of any origin and neuroepithelium.  Immature neural tissue/neuroepithelium > 4 low-power microscopic fields (4x objective) in any one slide. Mitotic activity is high.

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Grade / Category

Histological Features (Sertoli-Leydig Cell Tumors)

Note

Grade 1

(Well Differentiated)

Hollow or solid tubules composed of benign appearting Sertoli cells interspersed with variable numbers of Leydig cells that occasionally contain crystaloids of Reinke. These generally behave in a benign fashion.

*

Grade 2

(Moderately Differentiated)

A wide variety of patterns: Typically, they consist of immature Sertoli cells arranged diffusely in sheets, aggregates, or cords resembling embryonic testicular sex cords. The stromal component usually contains clusters of recognizable Leydig cells, but may be composed of indifferent spindle cells.

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Grade 3

(Poorly Differentiated / sarcomatoid)

Largely composed of spindled cells. These tumors may resemble sarcomas with prominent atypia and mitotic activity. The presence of cords of Sertoli cells, aggregates of Leydig cells, or other elements enables one to identify the lesion as a Sertoli-Leydig cell tumor.

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