Endometrial Stromal Sarcoma

Abstract
Endometrial stromal sarcoma (ESS) is a rare malignant tumor of the endometrium, occurring in the age group of 40-50 years.

History
50 year old female patient with menorrhagia, lower abdominal pain and heaviness.
On examination, found to have large abdominal pelvic mass.
US done and shows large mass inseparable from uterus with some vascularity.

Large lobulated mass inseparable from fundus of uterus and shows heterogenous enhancement with lots of vascularity around mass, more at anterior margin. Few small low density areas within mass representing cystic degeneration. Few small nodules around the large mass and are completely separate from the mass. The mass is causing compression over pelvis colon. The endometrium is clearly visible. The lesion appears to be solid. Rest of the exam within normal limit.

Differential Diagnosis
The differential diagnosis of a relatively hypervascular, soft-tissue mass arising from the apex of the uterus includes, large subserosal fibrod, or a primary malignancy of the uterus (such as leiomyosarcoma).

Diagnosis
Endometrial stromal sarcoma

Pathology Discussion
A total hysterectomy with was performed along with resection of surrounding nodules, omentum and colonic mucosa. The pathological findings were leading to the diagnosis of endometrial stromal sarcoma. This tumor does not involve the ovaries or fallopian tubes. Lymphovascular invasion was there. Extensive involvement of colonic wall with unremarkable colonic mucosa. Extemsive omental involvement and nodule was positive for deposit.

Radiology Discussion
Uterine sarcomas represent 2-5% of all uterine malignancies. There are three types: carcinosarcoma (also known as mixed mullerian tumor) is the most common, leiomyosarcoma is next, and endometrial stromal sarcoma (ESS) is the least common (<10% of uterine sarcomas). Endometrial stromal sarcomas are composed of cells that are identical to or closely resemble normal proliferative-phase endometrial stromal cells. These tumors may arise from the endometrium but can also be seen in the setting of adenomyosis or endometriosis.

Endometrial stromal sarcoma typically occurs in women between the ages of 42 and 59 years. Symptoms include abnormal uterine bleeding and pain. Risk factors are fairly nonspecific and include prior pelvic radiation therapy, age, and race (slightly higher incidence among blacks). There may also be hormonal factors, though this is not well understood. The differential diagnosis for ESS includes leiomyoma with cystic degeneration, leiomyosarcoma, and endometrial carcinoma. The subtle differences between these entities are best demonstrated with MRI.

On MR, endometrial stromal sarcomas appear as large tumors in the endometrial cavity and/or myometrium. The signal is typically high on T1-weighted images and heterogeneously high on T2-weighted images. The tumor margins are typically irregular, often with marginal nodular lesions. Intramyometrial worm-like nodular extensions may be visible. Hemorrhage and necrosis are common. Most ESS show greater enhancement than normal myometrium. Overall, ESS are difficult to differentiate from leiomyomas with cystic degeneration, leiomyosarcomas, and endometrial carcinomas.

There are, however, several imaging features that differentiate ESS from those other tumors. Endometrial carcinomas typically do not display irregular marginal lesions, marginal nodules or intramyometrial nodules. The avid enhancement pattern of ESS (relative to the myometrium) is also not typical for endometrial carcinomas. Leiomyomas and leiomyosarcomas generally do not have the high T2 signal that is characteristic of ESS. In addition, these tumors display a different pattern of enhancement; markedly increased signal after contrast is unusual. Finally, leiomyomas typically do not have irregular margins with small nodules (though these features may be seen in leiomyosarcomas).

CT done for further evaluation.

References:

References

Ueda M, et al. MR imaging findings of uterine endometrial stromal sarcoma: Differentiation from endometrial carcinoma. Eur Radiol. (2001) 11: 28-33.

Ueda M, et al. Uterine endometrial stromal sarcoma located in uterine myometrium: MRI appearance. Eur Radiol. (2000)10, 780-782.

Gandolfo, et al. Endometrial stromal sarcoma of the uterus: MR and US findings, Eur Radiol. (2000) 10, 776-779.