RESIDENT CASE STUDIES

August 21, 2003: Case 1

Table of Contents | List of Diagnoses | Case 1 | Case 2 | Case 3 | Case 4

69 year old female with history of hysterectomy 20 years ago, now presents with retroperitoneal and pelvic mass.

Discussion by Kathryn Rizzo, DO, PhD

A low-grade endometrial stromal sarcoma is composed of cells resembling those of the normal proliferative phase endometrium and has infiltrative margins and/or intravascular intrusion by tumor that can be seen on gross inspection.

Incidence: Rare

Prevalence: Most common in older premenopausal or postmenopausal woman

Distribution: Occurs at any age

Gross Appearance: Well-circumscribed mass, diffusely infiltrative mass, or multiple confluent masses. "Worm-like" masses within myometrium. Foci of hemorrhage, necrosis, or cystic degeneration.

Microscopic Appearance: 

• Extensively infiltrative margins, tumor within lymphovascular spaces and myometrium
• Arterioles that resemble the endometrial spiral arterioles are uniformly distributed throughout the tumor
• Variable numbers of mitotic figures, minimal atypical cells
• Foci of epithelioid differentiation appearing as glandular or sex cord-like elements, hemorrhage, necrosis may be present
• Calcification, decidualization, cystic degeneration, and foam cells may be present.

Diagnostic Criteria: 

• Uniform cells with scanty cytoplasm, resembles proliferative phase endometrial stroma cells
• Arborizing vascular pattern
• Thin-walled vasculature
• Variable mitotic rate, with the absence of atypical mitosis.

Immunostains:

• CD 10 positive, ER / PR positive

Differential Diagnosis:

• Endometrial stromal nodule
• High-grade stromal sarcoma
• Intravenous leiomyomatosis
• Carcinoma
• Gastrointestinal stromal tumor

References:

1. Stephen S Sternberg et al. (Eds): Diagnostic surgical pathology, Volume 1, 3rd edition. Lippincott William& Wilkins.
2. Enzinger FM, Weiss SW. Soft tissue tumors. St Louis: Mosby-Year Book; 1995.
3. Haber M. et al, Differential diagnosis in surgical pathology, Copyright 2002.
4. Yilmaz, A. et al. "Endometrial stromal sarcomas with unusual histologic features." Am.J. of Surg.Path. 26(9): 1142-1150, 2002.