Navigating Diagnostic Challenges: Distinguishing Between Endometrial Stromal Nodule and Endometrial Stromal Sarcoma in a Young Patient

Background: Endometrial stromal tumors, including Endometrial Stromal Nodule (ESN) and Endometrial Stromal Sarcoma (ESS), originate from the stromal tissue of the endometrium but differ significantly in their clinical behavior and histopathological characteristics. ESNs are benign, well-circumscribed tumors that do not infiltrate surrounding tissues, whereas ESS is malignant, with potential for local invasion and metastasis. Case Presentation: A 27-year-old, gravida 0 para 0, presented with ongoing heavy menstrual bleeding. Pelvic ultrasound revealed an anteverted uterus with a complex heterogeneous mass, initially suspected to be a submucosal leiomyoma. A hysteroscopic myomectomy was performed but terminated early due to reaching a maximal fluid deficit of 2,500 mL, caused by a large endocervical mass resembling a submucosal fibroid and difficulty maintaining hydrodistention. Histopathology suggested a differential diagnosis of ESN versus low-grade ESS, with myometrial invasion difficult to assess due to the fragmented curettage specimen. Immunohistochemical stains (IHS) were performed. Diffuse or patchy positivity for Caldesmon, CD10, Cyclin D1, Desmin, ER, PR, and SMA, is consistent with an endometrial stromal neoplasm (ESN), but it does not reliably differentiate between an endometrial stromal nodule (ESN) and low-grade endometrial stromal sarcoma (LG-ESS). Concerned about fertility preservation, the patient was distressed by the potential need for a hysterectomy. Pelvic MRI identified a prolapsed endometrial polypoid mass in the lower segment/endocervical cavity measuring 4.8 cm, with no adnexal masses or pelvic adenopathy. A Gynecologic Oncologist recommended a repeat hysteroscopic excision of the endocervical/lower uterine mass. Further work-up included negative CT scans of the abdomen, pelvis, and chest for metastatic disease. A repeat hysteroscopic excision was performed, successfully resecting the mass down to the endometrial base and possible myometrium. Despite these efforts, histopathology reports remained inconclusive in differentiating between ESN and low-grade ESS. The final pathology report indicated that the differential diagnosis includes both ESN, a benign lesion, and low-grade ESS. It noted that the distinction between these entities typically requires a hysterectomy specimen for definitive diagnosis. Clinical correlation was recommended. While uterine smooth muscle was present and some invasion appeared to be present, definitive criteria for low-grade stromal sarcoma were not identified. Clinical Insights: Endometrial Stromal Nodule (ESN): ESNs are benign and typically symptomatic, presenting with abnormal uterine bleeding in some cases. They are characterized by well-defined borders and uniform cells with no significant atypia. Surgical excision is usually curative. Endometrial Stromal Sarcoma (ESS): ESS is malignant, with low-grade forms capable of recurrence and metastasis. Histologically, ESS shows infiltrative growth with atypia and a higher mitotic rate. Treatment often involves a hysterectomy and may include additional therapies. Management Plan: Consultation with a Gynecologic Oncologist: Referral for specialized management, who recommended a chest, abdominal, and pelvic CT scan with IV contrast for accurate staging and assessment of disease spread. This imaging helps evaluate potential metastasis, guide treatment decisions, and establish a baseline for future monitoring. Pelvic MRI: To assess for myometrial invasion and further characterize the uterine lesion. Abdominal, pelvic, and chest CT: To exclude metastasis. Fertility-Sparing Options: Discussed conservative management if the lesion is benign or a low-grade malignancy without invasion. Hormonal Therapy: Consideration of progestins or GnRH analogs to manage symptoms. Regular Follow-up: Implemented a schedule for repeated imaging and clinical assessments. Conclusion: This case underscores the importance of distinguishing between ESN and ESS for accurate diagnosis and management. A multidisciplinary approach is essential to balance optimal medical care with the patient’s reproductive goals, emphasizing the need for continued monitoring and patient-centered care.