Uterus
Stromal tumors
Low grade endometrial stromal sarcoma


Minor changes: 3 May 2021

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PubMed search: low grade endometrial stromal sarcoma [title] uterus

Elizabeth Kertowidjojo, M.D., Ph.D., M.P.H.
Lora Hedrick Ellenson, M.D.
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Cite this page: Kertowidjojo E, Ellenson LH. Low grade endometrial stromal sarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusESSlowgrade.html. Accessed May 7th, 2021.
Definition / general
  • Malignant mesenchymal tumor comprised of cells resembling proliferative phase endometrial stroma with infiltrative growth or lymphovascular invasion
Essential features
  • Histologic features include permeative tongue-like islands of tumor cells composed of monotonous oval to spindle cells with minimal cytologic atypia, often demonstrating whorling around blood vessels; smooth muscle and sex cord-like differentiation are common
  • Diagnosis may require extensive sampling of the tumor myometrial interface to evaluate for invasion and exclude endometrial stromal nodule
  • Recurrent rearrangements involving JAZF1 and PHF1 are common, though absence does not preclude the diagnosis
Terminology
  • Endolymphatic stromal myosis
ICD coding
  • ICD-O: 8931/3 - endometrial stromal sarcoma, low grade
  • ICD-11: 2B5C & XH1S94 - endometrial stromal sarcoma, primary site and endometrial stromal sarcoma, low grade
Epidemiology
Sites
  • Uterus: more commonly the corpus than the cervix
  • Rarely extrauterine, usually associated with endometriosis
Clinical features
  • Abnormal uterine bleeding (most common), pelvic pain, uterine mass
  • Occasionally, patients present with metastases (most commonly lung, adnexal or nodal) (Adv Anat Pathol 2000;7:257)
Diagnosis
  • Radiologic findings on magnetic resonance imaging (MRI) (see radiology description)
  • Endometrial sampling may obtain diagnostic material in ~30%
Radiology description
Radiology images

Images hosted on other servers:

T2 and T1 weighted images

MRI of low grade endometrial stromal sarcoma

Prognostic factors
  • Typically indolent, with an overall 5 year survival of > 90% and a 10 year survival of 75%
  • Factor affecting prognosis: stage
  • Controversial factors: older age (> 50 years), mitotic index, necrosis (Oncology 2006;71:333)
  • Factors of uncertain significance: tumor size, lymphovascular invasion, hormonal status, ploidy (Adv Anat Pathol 2010;17:113)
Case reports
Treatment
Gross description
  • Poorly circumscribed soft yellow-tan to white nodules extending from the endometrium and invading into the myometrium
  • Worm-like plugs of tumor may be seen in the myometrium or lymphovascular channels (Am J Surg Pathol 1990;14:415)
  • Often with a polypoid endometrial component
  • May appear deceptively well circumscribed: extensive sampling of the tumor myometrial interface is necessary to rule out endometrial stromal nodule (Int J Gynecol Pathol 2014;33:374)
  • Hemorrhage and necrosis may be seen
Gross images

Contributed by Elizabeth Kertowidjojo, M.D., Ph.D., M.P.H.
Tan-yellow uterine mass

Tan-yellow uterine mass

Fleshy lobulated mass

Fleshy lobulated mass



Images hosted on other servers:

Yellow-brown
tumor mass and
additional infiltrating
tumor nodules

Macroscopically,
sarcoma resembles
uterine leiomyomas

Yellow tumor nodule with necrosis

Frozen section description
  • Spindle to oval cells with permeative growth into the myometrium
  • May be associated with a polypoid growth
  • Minimal cytologic atypia and low mitotic count
  • May display smooth muscle or sex cord-like differentiation
Frozen section images

Contributed by Elizabeth Kertowidjojo, M.D., Ph.D., M.P.H.
Polypoid mass

Polypoid mass

Low grade spindle cells

Low grade spindle cells

Infiltrative mass

Infiltrative mass

Microscopic (histologic) description
  • Irregular cellular islands, forming permeative tongue-like pattern of myometrial invasion with frequent vascular invasion
  • Monotonous oval to spindle cells with minimal cytologic atypia, vesicular chromatin and scant cytoplasm
  • Mitotic count is usually low (< 5/10 high power fields), necrosis is usually absent
  • Tumor cells may whorl around delicate arteriolar type vessels, reminiscent of proliferative phase endometrial stroma
  • May have admixed collagen bands / plaques and foamy histiocytes
  • May have smooth muscle differentiation, particularly in a starburst morphology, with collagen bands radiating towards the periphery of the nodule
  • Other reported types of differentiation: fibromyxoid / fibrous, sex cord-like, epithelioid, rhabdoid, endometrioid glands, pseudopapillae, clear cells, bizarre cells, adipose tissue (Mod Pathol 2016;29:S92)
Microscopic (histologic) images

Contributed by Elizabeth Kertowidjojo, M.D., Ph.D., M.P.H.
Tongue-like invasion

Tongue-like invasion

Monotonous tumor cells

Monotonous tumor cells

Whorling around vasculature

Whorling around vasculature

Smooth muscle differentiation

Smooth muscle differentiation


Desmin

Desmin

Sex cord-like growth

Sex cord-like growth

Endometrial curetting Endometrial curetting

Endometrial curetting



AFIP images

Dilated and thin walled vessels

Dilated vessels and sex cord-like structures

Extensive myometrial infiltration

Myometrial infiltration by uniform small tumor cells

Nests and sex cord-like arrangements

Myometrial lymphatics

Cytology description
  • Resembles benign endometrial stromal cells
  • Moderate to marked cellularity composed of single cells and clusters of bland cells with scant cytoplasm, small round to spindle nuclei with fine chromatin (Acta Cytol 2007;51:461)
  • Interspersed delicate blood vessels may be present
  • Distinction between low grade endometrial stromal sarcoma and endometrial stromal nodule cannot be made based on cytology, as it requires evaluation of the tumor myometrium interface
  • Distinction between low grade endometrial stromal sarcoma and other monomorphic spindle cell neoplasm is difficult on cytology, especially without immunohistochemistry
Cytology images

Contributed by Elizabeth Kertowidjojo, M.D., Ph.D., M.P.H.
Lung fine needle aspiration

Lung fine needle aspiration

Lung fine needle aspiration cell block

Lung fine needle aspiration cell block

Positive stains
Negative stains
Molecular / cytogenetics description
Molecular / cytogenetics images

Images hosted on other servers:

JAZF1-SUZ12 dual fusion probe

MBTD1-CXorf67 dual fusion probe

Videos

Endometrial stromal sarcoma

Uterine mesenchymal neoplasms

Sample pathology report
  • Uterus, hysterectomy:
    • Endometrial stromal sarcoma, low grade (see synoptic report)
    • Tumor size: 9 cm
    • Lymphovascular invasion identified
    • Surgical margins uninvolved
Differential diagnosis
  • Endometrial stromal nodule:
    • Absent to minimal myometrial invasion (≤ 3 protrusions, each measuring < 3 mm) and no lymphovascular invasion
  • High grade endometrial stromal sarcoma:
    • Presence of a high grade component with cytologic atypia and elevated mitotic count
    • Frequently positive for cyclin D1 and BCOR while negative for ER
    • YWHAE-NUTM2A/B fusion, BCOR fusions or internal tandem duplication
  • Cellular leiomyoma:
    • Fascicular growth, large thick walled blood vessels, cleft-like spaces
    • Lack JAZF1 or PHF1 fusions
  • Leiomyosarcoma:
    • Marked cytologic atypia, mitotic activity and necrosis
    • Large thick walled blood vessels
    • Lack JAZF1 or PHF1 fusions
  • Uterine tumor resembling ovarian sex cord tumor:
    • Absence of any conventional endometrial stromal component
    • ESR1 or GREB1 fusions in a subset
  • Endometrial polyp:
    • No expansile growth or displacement of adjacent endometrium
  • Gland poor adenomyosis:
    • No confluent growth or displacement of myometrium
Board review style question #1


The uterine tumor illustrated in the figures above is best diagnosed as

  1. Cellular leiomyoma
  2. Endometrial stromal nodule
  3. Endometrioid carcinoma
  4. Low grade endometrial stromal sarcoma
  5. Uterine tumor resembling ovarian sex cord tumor
Board review style answer #1
D. Low grade endometrial stromal sarcoma. The tumor shows a polypoid component, as well as a characteristic permeative tongue-like invasion pattern seen on low power. The presence of invasion rules out an endometrial stromal nodule (answer B) and cellular leiomyoma (answer A). The lack of any glandular component rules out endometrioid carcinoma (answer C). While low grade endometrial stromal sarcoma can have sex cord-like differentiation, the presence of conventional low grade endometrial stromal sarcoma rules out uterine tumor resembling ovarian sex cord tumor (answer E).

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Reference: Low grade endometrial stromal sarcoma
Board review style question #2
Which of the following can reliably diagnose low grade endometrial stromal sarcoma?

  1. Endometrial biopsy
  2. Hysterectomy
  3. Myomectomy
  4. Presenting symptoms and clinical history
  5. Ultrasound
Board review style answer #2
B. Hysterectomy. The presenting symptoms and clinical findings in low grade endometrial stromal sarcoma are nonspecific, including abnormal uterine bleeding, pelvic pain and uterine mass. While ultrasound can detect a uterine mass, distinguishing low grade endometrial stromal sarcoma from other entities such as endometrial stromal nodule and leiomyoma can be difficult. While biopsy and myomectomy may obtain diagnostic material, low grade endometrial stromal sarcoma is distinguished from endometrial stromal nodule by its invasive growth pattern, which cannot be appreciated on limited sampling.

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Reference: Low grade endometrial stromal sarcoma
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