Pathology Manual: Gynecologic Oncology

Histologic Classification of Malignant Neoplasms of Uterine Corpus (ISGYP - WHO)

1. Endometrial Carcinoma
   1. Endometrioid
      1. Adenocarcinoma
         1. Villoglandular
         2. Secretory
         3. Ciliated cell
      2. Adenocarcinoma with squamous differentiation (preferred designation)
         1. Adenocarcinoma with squamous metaplasia (adenoacanthoma, optional terminology)
         2. Adenosquamous carcinoma (optional terminology)
   2. Serous adenocarcinoma
   3. Clear cell adenocarcinoma
   4. Mucinous adenocarcinoma
   5. Squamous cell carcinoma
   6. Mixed carcinoma
   7. Undifferentiated carcinoma
2. Non-epithelial Neoplasms
   1. Endometrial stromal tumors
      1. Stromal nodule
      2. Low grade stromal sarcoma
      3. High grade stromal sarcoma
   2. Smooth muscle tumor of uncertain malignant potential
   3. Leiomyosarcoma
      1. Epithelioid
      2. Myxoid
   4. Mixed endometrial stromal and smooth muscle tumor
   5. Poorly differentiated (undifferentiated) endometrial sarcoma
   6. Other soft tissue tumors
      1. Homologous
      2. Heterologous
3. Mixed epithelial - nonepithelial tumors
   1. Adenosarcoma
      1. Homologous
      2. Heterologous
      3. With high grade stromal overgrowth (see notes)
   2. Carcinosarcoma (malignant mixed mesodermal tumor; malignant mixed Mullerian tumor)
      1. Homologous
      2. Heterologous
   3. Carcinofibroma
4. Miscellaneous
   1. Sex cord-like tumors
   2. Germ cell neoplasms
   3. Neuroectodermal tumors
   4. Lymphoma
   5. Other
5. Metastatic tumors

Notes:

1. Serous carcinoma and clear cell carcinoma should comprise more than 50% of a tumor before being designated in those categories when there are mixed components (by agreement of the GOG Pathology Committee).
2. An epithelial subtype must be at least 10% of the total volume to designate the tumor mixed.
3. Low grade stromal sarcomas are cytologically and architecturally bland with evidence of infiltrative behavior. Classically <10 mitoses/10 hpf, but not a strict criterion.High grade stromal sarcomas are cytologically poorly differentiated with infiltrative behavior, necrosis, and atypical mitoses, classically >10/10 hpf.
4. Diagnosis of smooth muscle tumors of uncertain malignant potential: (suggested)(1,2)
   • Cytologic atypia, 2-5 mitoses/10 hpf
   • Hypercellular, no atypia, 5-10 mitoses/hpf
   • No hypercellularity or atypia, 10-15 mitoses/hpf
   • Infiltrating margin, 5-10 mitoses/hpf
   • Atypical mitoses and/or necrosis
   • Epithelioid, 2-5 mitoses/10 hpf
   • Symplastic, 2-5/10 hpf
   • Vascular invasion, 2-5 mitoses/10 hpf
   • Intravenous leiomyomatosis, 2-5 mitoses/10 hpf
   • Parasitic leiomyoma, 5-9 mitoses/10 hpf
5. To consider a tumor a primary squamous cell carcinoma or mucinous carcinoma of endometrium, concurrent cervical carcinoma of the same cell type must be absent.
6. Adenosarcoma with high grade stromal overgrowth should be specifically noted due to its poor prognosis.
   1. Atlas of Tumor Pathology, Third Series, Tumors of Uterine Corpus and Gestational Trophoblastic Disease, Silverberg SG, Kurman RJ, AFIP 1992.
   2. Kempson RL, Hendrickson MR. Pure mesenchymal neoplasms of the uterine corpus. In: Fox H, ed. Hanes and Taylor. Obstetrical and Gynecological Pathology. 3rd ed. Edinburgh: Churchill Livingston, 411-56, 1987.
   3. Norris HJ, Taylor HB. Mesenchymal tumors of the uterus. I. A clinical and pathological study of 53 endometrial stromal tumors. Cancer 1966, 19:755-66.
   4. Evans HL. Endometrial stromal sarcoma and poorly differentiated endometrial sarcoma. Cancer 1982, 50:2170-82.
   5. Kempson RL, Hendrickson MR. Pure mesenchymal neoplasms of the uterine corpus. In: Fox H, ed Hanes and Taylor. Obstetrical and Gynecological Pathology. 3rd ed. Edinburgh: Churchill Livingstone 1987:411-56.

Grading - Endometrial Carcinoma

Grade 1

less than or equal to 5% of solid growth pattern (morules or squamous growth are not considered solid pattern).

Grade 2

6-50% of solid growth pattern

Grade 3

> 50% of solid growth pattern

1. Nuclear morphology inappropriately atypical for architectural grade raises carcinoma grade by one.
2. Adenocarcinoma with squamous differentiation is graded according to architectural grade of the glandular component.
3. Serous carcinoma, pure clear cell, and pure squamous cell as yet do not have a clear system for grading identified, though they are generally considered to be high grade (grade 3) based on behavior.

 

Surgical Staging of Carcinoma of the Corpus Uteri

FIGO Classification - 1988(1)

Stage IA:

Tumor limited to endometrium
Grade 1,2,3

Stage IB:

Invasion to < 1/2 myometrium*
Grade 1,2,3

Stage IC:

Invasion to > 1/2 myometrium*
Grade 1,2,3

Stage IIA:

Endocervical glandular/surface involvement only
Grade 1,2,3

Stage IIB:

Cervical stromal invasion
Grade 1,2,3

Stage IIIA:

Tumor invades serosa and/or adnexa and/or positive peritoneal cytology
Grade 1,2,3

Stage IIIB:

Vaginal metastases
Grade 1,2,3

Stage IIIC:

Metastases to pelvic and/or para-aortic lymph nodes
Grade 1,2,3

Stage IVA:

Tumor invasion of bladder and/or bowel mucosa

Stage IVB:

Distant metastases including intra-abdominal and/or inguinal lymph node

*Depth of invasion should be evaluated at the deepest point with actual measurements of tumor depth and myometrial thickness recorded from the microscopic slides.

1. Gynecol Oncol 35:125-7, 1989.

Clinical Staging of Endometrial Carcinoma

(FIGO 1971)

Stage I:

Carcinoma is confined to the corpus. IA; Grade 1,2,3: The length of the uterine cavity is 8 cm or less. IB; Grade 1,2,3: The length of the uterine cavity is more than 8 cm.

Stage II:

Carcinoma involving the corpus and the cervix with histologic proof of endocervical involvement.

Stage III:

The carcinoma has extended outside the uterus, but not outside the true pelvis.

Stage IV:

The carcinoma has extended outside the uterus, but not outside the true pelvis or has obviously involved the mucosa of the bladder or rectum.Bullous edema as such does not permit allotment of a case to Stage IV.

This is a clinical staging scheme and is based on findings of physical examination and laboratory and x-ray studies. Results of histologic examination beyond that of the primary site are not considered in establishing the clinical stage except as noted above. This system should be used if preoperative radiation precludes adequate histologic evaluation of resected specimens. Staging scheme used should be consistent within a protocol, as much as possible.

Staging - Sarcoma of the Corpus Uteri

FIGO Classification - 1976

Stage 0:

Histologic findings suspicious of malignancy.
(Cases of Stage 0 should not be included in any therapeutic statistics).

Stage I:

The sarcoma is confined to the corpus.

Depth of uterine cavity 8 cm or less.

Depth of uterine cavity greater than 8 cm.

Stage II:

The sarcoma has involved both cervix and corpus.

Stage III:

The sarcoma has extended outside the uterus but not outside the true pelvis.

Stage IV:

The sarcoma has extended outside the true pelvis or has obviously involved the mucosa of the bladder or rectum.

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