Endometrial Stromal Nodule

Author Information

Chaudhari J*, Patil D**, Shende A***, Chauhan AR****.

(* Assistant Professor, Pathology; ** Third Year Resident, Obstetrics Gynecology; *** Third Year Resident, Pathology; **** Additional Professor, Obstetrics Gynecology. Seth GS Medical College & KEM Hospital, Mumbai, India.)

Abstract

Endometrial stromal tumors are rare, and can be benign or malignant. Benign endometrial stromal tumors are also known as stromal nodules; endometrial sarcomas are malignant stromal tumors, which can be the more common low-grade sarcomas or high grade sarcomas.  Endometrial stromal nodules are well- circumscribed, expansile, and do not invade the myometrium. Conversely, endometrial sarcomas infiltrate the myometrium, invade vascular spaces, and have the capability to invade adjacent tissues and metastasize. Extensive sampling of the interphase between tumor and myometrium is of utmost importance to distinguish between stromal nodule and sarcoma. We present a case of endometrial stromal nodule (ESN) in a patient of rheumatic heart disease.

Introduction

Tumors of endometrial stroma are very rare mesenchymal tumors of the uterus with architectural and cytological features suggestive of endometrial stromal cells.^[1] The World Health Organization classification of tumors of the breast and female genital organs divides uterine stromal neoplasms into three groups: benign endometrial stromal nodule (ESN), low-grade endometrial stromal sarcoma (LGESS), and undifferentiated endometrial sarcoma (UES).^[2] ESN, though cytologically similar to low-grade stromal sarcoma, has a well-circumscribed, expansile margin and is benign. On the other hand, UES is a rare but highly malignant sarcoma which lacks overt endometrial stromal differentiation.^{[1, 2]}

Case History

A 38 year old female, known case of rheumatic heart disease with mitral stenosis since 20 years, presented with dull pain and discomfort in the lower abdomen since 5 months. Abdominal and pelvic examination revealed a painless pelvic mass of approximately 14 weeks’ size, with a palpable 8 x 8 cm mass on right posterior-lateral uterine wall. Pelvic ultrasound showed bulky uterus of 11.5 x 6.1 x 8.7 cm size, with 8.2 x 7.6 x 7.1 cm right postero-lateral wall fibroid with multiple cystic areas within, suggestive of cystic degeneration of fibroid. Both ovaries were visualized; presence of a left ovarian simple cyst of 3.7 x 2.9 cm size without septations or solid component within it were noted. Laboratory investigations were normal. Total abdominal hysterectomy was done which was uneventful. Intra operative findings were suggestive of uterine enlargement, bilateral normal ovaries and bilateral paraovarian cysts, approximately 4 x 5 cm size. The uterus was enlarged and on opening a large well circumscribed mass measuring 8 x 7x 4 cm was seen in myometrium which was bulging above the surface, yellow white with few cystic areas, as seen in Figure 1. 

Figure 1. A well circumscribed mass in the uterus with yellow white cut surface and few cystic areas

On microscopy, it showed a non-encapsulated circumscribed mass showing small cells with oval nuclei, granular chromatin, scanty clear to eosinophilic cytoplasm arranged in sheets with arteriole sized blood vessels. Only three tiny tongue- like projections were seen invading less than 3 mm depth in the myometrium. There were no areas of necrosis, mitosis or nuclear atypia, nor was there definite vascular invasion. The histological features were typical of endometrial stromal nodule (Figure 2).

Figure 2. Circumscribed mass showing small oval cells and arteriole sized blood vessels. (HE 400X) 

Discussion

Endometrial stromal tumours are one of the least common neoplasms of the uterus, with a reported incidence of about 2 per million women annually. [3] The clinical presentation is nonspecific; the patients may be asymptomatic or may present with significant vaginal bleeding, pelvic or abdominal pain or discomfort. [4] There is no reliable preoperative diagnostic procedure to identify this tumour; hysterectomy is the treatment of choice and diagnosis is based on microscopic examination. ESNs are grossly well circumscribed and lack permeative infiltration of an ESS. But some of them have a little irregularity of the margin and may even be minimally invasive i.e. less than 3 mm invasion and less than 3 foci [1, 4] Although the presence of an EST is sometimes established by curettage, a definitive diagnosis of LGESS can be made if myometrial and/or vascular invasion is identified in the tissue fragments. A hysterectomy is usually required to permit thorough evaluation of the tumor margin; this is necessary to distinguish a stromal sarcoma from a benign stromal nodule. [4]Although ESS resembles non-neoplastic proliferative endometrial stroma, they are morphologically heterogeneous. Fibroblastic and smooth-muscle differentiation may be seen and may erroneously suggest myometrial infiltration. [4] ESNs like other uterine neoplasms of stromal origin occur primarily in older postmenopausal women, in whom hysterectomy is usually done. [2, 3, 4] In women of reproductive age who desire fertility conservation, diagnostic sonography and hysteroscopy may be used to follow up tumor growth. In some cases, progesterone therapy with local excision may be successful. [4] The prognosis is excellent once the diagnosis is confirmed.

References

1. Baker Patricia, Oliva Esther. Endometrial stromal tumours of the uterus: a practical approach using conventional morphology and ancillary techniques. J Clin Pathol 2007; 60 (3): 235–243
2. Tavassoli FA, Devilee P. World Health Organization Classification of Tumors: Pathology and genetics of the breast and female genital organs, IARC Press; Lyon; 2003: 230-50
3. Zaloudek C, Hendrickson MR. Mesenchymal tumors of the uterus. In: Kurman RJ. Blaustein’s Pathology of the Female Genital Tract. 5th ed. Springer, Springer–Verlag, New York, Berlin, Heidelberg 2001: 561-615.
4. Sahande Elagoz, Fügen Kıvanc, Handan Aker, Sema Arici, Hatice Ozer, Tevfik Güvenal et al. Endometrial stromal tumors – a report of 5 cases. Aegean Pathology Journal 2005; 2: 140–45.

Citation

Chaudhari J, Patil D, Shende A, Chauhan AR. Endometrial Stromal Nodule. JPGO Volume 1 Issue 11. Available from: http://www.jpgo.org/2014/11/endometrial-stromal-nodule.html