Table of Contents
Definition / general | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Molecular / cytogenetics description | Differential diagnosis | Additional referencesCite this page: Pernick N. Low grade endometrial stromal sarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusESSlowgrade.html. Accessed January 16th, 2021.
Definition / general
- Also known as endolymphatic stromal myosis
- Slow clinical progression with repeated local recurrences
- 50% recur (may take 10 years), 15% die of metastases (lung) but may be 20 - 30 years later
- Rarely arise from ovary, vagina and peritoneum
Case reports
- 53 year old woman with vaginal bleeding (Case of Week #246)
Treatment
- Adjuvant therapy may reduce recurrence (Ann Oncol 2010;21:2102)
Gross description
- Polypoid mass extending into broad ligament, ovaries and fallopian tubes
- Lymphatic tumor plugs may appear as yellow, ropy or ball-like masses
Gross images
Microscopic (histologic) description
- Monotonous ovoid to spindly cells with minimal cytoplasm intimately associated with prominent arterioles, closely resembles proliferative endometrial stroma
- Up to 10 - 15 mitotic figures per 10 HPF in most active areas
- Tongue-like infiltration between muscle bundles of myometrium
- Angiolymphatic invasion common
- May exhibit myxoid, epithelioid and fibrous change
- May have foam cells or hyalinization
Microscopic (histologic) images
AFIP images

Extensive myometrial infiltration
(Note also slit-like spaces around
tumor masses representing
vascular involvement)

Myometrial lymphatics expanded and
infiltrated by tumor; lobulated contour
of this intravascular tumor is unusual,
resembling intravenous leiomyomatosis
Images hosted on other servers:
Cytology description
- Clean background; usually moderate to marked cellularity with both single cells and stromal fragments; usually also blood vessels interspersed between stromal cell clusters; cells predominantly spindled with scant to moderate cytoplasm, round to ovoid nuclei, fine chromatin; rare mitotic figures, nuclei (Am J Clin Pathol 2007;128:265)
Positive stains
- ER, PR
- Diffuse, strong nuclear immunoreactivity with beta-catenin in 67% (Mod Pathol 2008;21:756)
- AE1 / AE3 in 50% (usually due to CK19+, (Hum Pathol 2008;39:1459)
Negative stains
- Mucin, glycogen
Molecular / cytogenetics description
- JAZF1-JJAZ1 fusion transcript in 50% - 60% (Am J Surg Pathol 2007;31:65)
Differential diagnosis
- Stromal nodule: not infiltrative, no angiolymphatic invasion
- Adenomyosis with sparse glands: usually incidental finding in post-menopausal woman with small and atrophic stromal cells, typical areas of adenomyosis usually present
- Cellular leiomyoma: no infiltration, no angiolymphatic invasion
- Menstrual endometrium within vessels: usually glands are uniformly distributed with bland stroma
- Metastatic lobular carcinoma: check clinical history, strongly keratin+
- Pseudosarcomatous changes in the stroma
- Fragmented lymphoid follicles in biopsies or curettings
- Intravascular leiomyomatosis
Additional references