A 63-year-old woman with two pregnancies—both normal vaginal delivery (NVD)—and menopause at age 50 years, referred to Hafte Tir Hospital (Tehran, Iran) on August 2021 due to a 6-month history of abdominal pain and vaginal spotting. There was no particular disease in the family or personal history. The patient was evaluated by transabdominal sonography of the uterus and ovaries, which showed a mass of 55 × 29 mm2 on the endometrial cavity in favor of uterus myoma. The laboratory investigation of Cell blood counts (WBC: 4.5 103/μL, Hb: 11 g/dL, Plt: 250 103/mm3 and other basic tests related to the liver (AST: 15 U/L, ALT: 19 U/L, ALP: 115 IU/L, Total Billirubin: 1.08 mg/dL and kidney (urea: 36 mg/dL, Creatinine: 0.6 mg/dL) were reported. A hysterectomy was done due to severe bleeding. A polypoid tumoral lesion measuring 7.5 cm in the postoperative gross pathology was observed, which occupied the endometrial cavity. The microscopic examination showed a fungating mass composed of hypercellular endometrial-like stroma, covered by a single layer of flattened cells forming large numbers of polypoid projections. The stroma was mildly hypercellular with condensation around the surface epithelium. Areas of stromal edema were also seen. Mild nuclear pleomorphism of stromal spindle cells was seen. Mitotic figures were estimated at 4–5/10 hpf. No stromal invasion was identified. Immunohistochemical staining was performed to confirm the diagnosis. The IHC study was positive for Panck, SMA, CD10, Desmin, ER, PR, and P53 and negative for WT1. According to these findings, the diagnosis was compatible with Mullerian adenosarcoma of the endometrium, with no myometrial invasion and positive ki76 staining in about 10% of neoplastic stromal components. One month after TAHBSO surgery, a computed tomography scan (CT scan) of the chest, the abdomen, and the pelvis with and without contrast injection was done. Soft tissue was observed in the vaginal cuff in the abdominal and pelvic CT. Regarding the inoperable residue, the patient underwent four courses of adjuvant chemotherapy (Ifosfamide, Mesna, Adriamycin), and after 1 month, she underwent whole pelvic radiation with a dose of 50.4 Gy/28 fr. 3 months after the completion of treatment, the patient underwent Pelvis MRI with and without GAD, which showed a complete response. Currently, the patient has no evidence of recurrence or metastasis after 9 months of treatment.