Stromal tumors
Low grade endometrial stromal sarcoma

Topic Completed: 1 January 2012

Minor changes: 13 August 2020

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PubMed search: low grade endometrial stromal sarcoma [title]

Nat Pernick, M.D.
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Cite 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
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

Images hosted on other servers:

Yellow brown
tumor mass and
additional infiltrating
tumor nodules

Sarcoma macro-
scopically similar
to a uterine

Yellow tumor nodule with necrosis

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

Dilated and slit-like thin walled vessels are prominent

Dilated vessels and sex cord-like structures

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

Myometrial infiltration by uniform small tumor cells

Nests and sex cord-
like arrangements
blend with intervening
stromal cells

Myometrial lymphatics expanded and
infiltrated by tumor; lobulated contour
of this intravascular tumor is unusual,
resembling intravenous leiomyomatosis

Images hosted on other servers:

Low grade endometrial stromal sarcoma with intravenous extension to the heart

Well defined, cell rich tumor cell aggregates with tongue shaped extensions

Spindled tumor cells with scant cytoplasm and minimal atypia

Intratumoral vessels resembling spiral arteries

Stromal sarcoma on left, PR+

Stromal sarcoma, CD10+

Myometrium stains smooth muscular actin+

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
Negative stains
  • Mucin, glycogen
Molecular / cytogenetics description
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
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