Uterus
Stromal tumors
Endometrial stromal nodule
Editorial Board Member: Gulisa Turashvili, M.D., Ph.D.
Deputy Editor-in-Chief: Jennifer A. Bennett, M.D.
Last author update: 2 December 2021
Last staff update: 2 December 2021
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed search: endometrial stromal nodule uterus
Table of Contents
Definition / general | Essential features | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Radiology description | Prognostic factors | Case reports | Treatment | Gross description | Gross images | Frozen section description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Molecular / cytogenetics description | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Jeyachandran D, Desouki MM. Endometrial stromal nodule. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusstromalnodule.html. Accessed December 24th, 2024.
Definition / general
- Benign tumor composed of cells reminiscent of proliferative phase endometrial stroma with absent or minimal myometrial invasion (< 3 mm and < 3 protrusions) and lacking vascular invasion
Essential features
- Benign tumor composed of cells reminiscent of proliferative phase endometrial stroma with absent or minimal myometrial invasion (< 3 mm and < 3 protrusions) and lacking vascular invasion
- Can be cystic, have necrosis and hemorrhage
- Excellent prognosis if completely excised
ICD coding
- ICD-10: D26.1 - other benign neoplasm of corpus uteri (endometrial - stromal)
Epidemiology
- Rare tumor
- Occurs at any age (mostly in the fifth and sixth decades)
- Associated with hypoestrogenism, tamoxifen therapy, radiation
Sites
- Corpus > cervix > ovary
Pathophysiology
- Unknown
Etiology
- Unknown
Clinical features
- Usually asymptomatic / incidental
- Abnormal vaginal bleeding
- Pelvic mass
Diagnosis
- Diagnosis of endometrial stromal nodule should be made only on hysterectomy specimen after extensive sampling (Adv Anat Pathol 2014;21:383, Int J Gynecol Pathol 2020;39:221)
Radiology description
- Nonspecific, irregular nodular lesion (Case Rep Med 2011;2011:260647)
Prognostic factors
- Excellent prognosis if completely excised (hysterectomy)
Case reports
- 38 year old woman with nausea and abnormal uterine bleeding (Case Rep Obstet Gynecol 2015;2015:376817)
- 45 year old woman with presurgical diagnosis of adnexal mass or uterine tumor (Case Rep Med 2011;2011:260647)
Treatment
- Hysterectomy if fertility is complete or not desired
- If fertility preservation is desired, conservative excision followed by hysteroscopy to monitor for regrowth
- Conservative excision may be adequate but usually limits ability to sample margins
Gross description
- Well circumscribed, nonencapsulated, soft, fleshy yellow, solitary lesion with size ranging from 1 - 12 cm
- Tumors usually grow in an expansile, noninfiltrating pattern with a smooth margin
- Rarely, can show some irregularities but no intravascular component
- Usually located in the endometrial cavity (polypoid mass) but can also be seen in myometrium
- Can be cystic
- Can have necrosis and hemorrhage
Gross images
Contributed by Devi Jeyachandran, M.D.
Polypoid uterine tumor
Images hosted on other servers:
Uterine tumor
Frozen section description
- If sent for frozen, it may be difficult to differentiate with other spindle cell lesions
- Can be reported as spindle cell proliferation; final diagnosis deferred to permanent
Microscopic (histologic) description
- Monotonous proliferations of bland endometrial stromal cells
- Expansive growth pattern (not infiltrating) at the margin
- Infiltration, if present, should be < 3 mm and < 3 protrusions
- Usually prominent proliferative type arterioles and can sometimes show hyalinized walls
- Collagen bands, plaques, infarct-like necrosis, hemorrhage and degenerative changes (cholesterol clefts, myxoid change and histiocytes) can be present
- Large, thick blood vessels are uncommon; if present, usually are seen at tumor - myometrium interface
- May have sex cord-like differentiation, epithelioid morphology, rhabdoid features, clear cells, granular cytoplasm, pseudopapillary, glandular element, fat cells, multinucleated giant cells, bizarre cells, myxoid change
- No angiolymphatic invasion should be present
- Mitotic activity is usually < 10 per 10 high power fields
- Note: foci of smooth muscle metaplasia within the tumor should not be interpreted as myometrial invasion at the edge of the tumor
Microscopic (histologic) images
Contributed by Devi Jeyachandran, M.D.
Bland stromal cells
Expansive growth
Proliferative type arterioles
Bland stromal cells
CD10 expression
ER expression
PR expression
WT1 expression
SMA expression
AE1 / AE3 expression
Desmin expression
Positive stains
- CD10, ER, PR, WT1, SMA, cytokeratin
- Interferon induced transmembrane protein 1 (IFITM1) has a higher specificity than CD10 in the distinction between endometrial stromal and smooth muscle neoplasms (particularly low grade endometrial stromal sarcoma) (Mod Pathol 2014;27:569)
- 10 - 25% of tumor cells are negative for CD10 (Am J Surg Pathol 2002;26:403)
- Tumors with sex cord-like differentiation may be positive for inhibin, calretinin, MelanA, CD99
Negative stains
- Desmin, h-caldesmon (but can be positive if smooth muscle or sex cord-like differentiation is present)
- CD34 (rarely positive)
Molecular / cytogenetics description
- t(7;17) most common JAZF1-SUZ12
- PHF1 gene rearrangements (especially if sex cord-like areas are present)
Sample pathology report
- Uterus, cervix, fallopian tubes and ovaries, total hysterectomy and bilateral salpingo-oophorectomy:
- Endometrial stromal nodule (see comment)
- Comment: The mass is extensively sampled and the microscopic examination shows bland spindle cell proliferation resembling endometrial stroma with rare mitosis and proliferative type arterioles. Given the morphology and noninfiltrative growth pattern along with strong CD10 positivity, the above diagnosis is rendered.
- Endometrium, curettage:
- Spindle cell proliferation, final classification deferred to resection specimen (see comment)
- Comment: The biopsy shows bland spindle cell proliferation resembling endometrial stroma with rare mitosis and proliferative type arterioles. These features favor a low grade endometrial stromal tumor but distinction between an endometrial stromal nodule versus low grade endometrial stromal sarcoma cannot be made on a limited sampling.
Differential diagnosis
- Cellular leiomyoma:
- Endometrial polyp, especially in curettage:
- Admixed endometrial glands
- Stroma lacks mitoses
- Presence of thick walled blood vessels
- Low grade endometrial stromal sarcoma:
- Infiltrative growth pattern and angiolymphatic invasion
- Gland poor and intravascular adenomyosis:
- Areas of conventional adenomyosis
- Not mass forming
- No expansile growth pattern
- Uterine tumor resembling ovarian sex cord stromal tumor:
- Tubules resembling ovarian sex cord tumors
- No prominent arterioles
- NCOA1-3 rearrangement (Am J Surg Pathol 2020;44:30)
- Embryonal rhabdomyosarcoma:
- Presence of cambium layer
- Rhabdomyoblasts
- Brisk mitoses
- Myogenin / MyoD1 positivity
- May harbor mutations in DICER1, TP53, PI3K / AKT / mTOR pathway and KRAS / NRAS (Mod Pathol 2021;34:1750)
- Primitive neuroectodermal tumor:
- Small blue cells without delicate vasculature
- Positive for FLI1, WT1
- EWSR1-FLI1, EWRSR1-ERG fusions (N Engl J Med 2021;384:154)
Board review style question #1
The diagnosis of endometrial stromal nodule versus low grade endometrial stromal sarcoma is based on
- Depth of invasion (superficial versus deep)
- Infiltrative growth pattern and angiolymphatic invasion
- Presence and absence of molecular alteration
- Size of the tumor
Board review style answer #1
B. Infiltrative growth pattern and angiolymphatic invasion
Comment Here
Reference: Endometrial stromal nodule
Comment Here
Reference: Endometrial stromal nodule
Board review style question #2
A 56 year old woman presents with abnormal uterine bleeding and a polypoid mass in the uterus. The tumor is well circumscribed with bland spindled cells and delicate vasculature. No infiltrative pattern, mitoses, atypia, necrosis or angiolymphatic invasion were identified. No myometrial invasion is identified. The tumor cells are strongly and diffusely positive for CD10, ER and SMA and negative for desmin, caldesmon and MelanA. What type of tumor does this likely represent?
- Endometrial polyp
- Endometrial stromal nodule
- Endometrial stromal sarcoma, low grade
- Gland poor adenomyosis
- Leiomyoma
Board review style answer #2
