Introduction/Background Endometrial stromal tumors are classified according to their histological characteristics as Endometrial Stromal Nodule (ESN), Low-grade Endometrial Stromal Sarcoma (LGESS), High-grade Endometrial Stromal Sarcoma (HGESS) and Undifferentiated Uterine Sarcoma (UUS). ESN is a rare neoplasm cytologically similar to low-grade endometrial stromal sarcoma, but it is distinguished by its non-invasive capacity and is considered a benign lesion.

Methodology We describe two cases of women with endometrial stromal nodules who underwent total abdominal hysterectomy. The patients were 49 and 54 years old, respectively, and presented with abnormal menstrual bleeding.

Results Histopathologically, several rounded tumors with a myomatous appearance were identified, the largest being 7 x 5 cm, and a 2 cm vascularized lesion with cellular tabs reminiscent of the endometrial stroma without lymphovascular invasion or mitosis.The morphological and immunohistochemical findings are compatible with an endometrial stromal nodule. Low cell proliferation (4 mitoses/10 high power fields and Ki 67 < 5%). Positivity for CD 10 and ER and RP, focally for Vimentin and negativity for Caldesmon and Actin.

Conclusion ESN is described as a nodule composed of endometrial stromal cells located in the myometrium. It is characterized by its circumscribed and non-invasive nature. From the histological point of view, cell tabs simulating infiltration of less than 3 mm and without vascular invasion are typical. Generally, the definitive diagnosis is made in a hysterectomy sample, because an evaluation of the tumor edges is required to eliminate an LGESS and immunohistochemical criteria are required.