Nobuhiko Suzuki, Yuko Horiuchi, Naoyuki Iwahashi, Yurina Mikasa, Kazuhiko Ino
Uterine adenosarcoma is a rare biphasic malignancy composed of benign epithelial and malignant stromal components. Adenosarcoma with sarcomatous overgrowth is an aggressive subtype associated with rapid progression and a poor prognosis. We report a case of uterine adenosarcoma with sarcomatous overgrowth diagnosed through the histopathological evaluation of a hysteroscopic polypectomy specimen. A 47-year-old woman presented to a local physician with abnormal uterine bleeding. Pelvic magnetic resonance imaging revealed a 5.5-cm polypoid lesion arising from the uterine corpus and protruding into the endometrial cavity, along with an intramyometrial mass. Hysteroscopic polypectomy was performed, and histopathological examination revealed uterine adenosarcoma, prompting referral to our institution. Positron emission tomography/computed tomography demonstrated fluorodeoxyglucose uptake in both the endometrial lesion and intramyometrial mass, without evidence of distant metastasis. The patient underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy. Histopathological examination of the resected uterus showed mildly atypical glandular epithelium surrounded by densely cellular, high-grade malignant stromal cells, together with extensive high-grade sarcomatous overgrowth involving the myometrium. Immunohistochemical staining demonstrated strong CD10 positivity and focal weak h-caldesmon positivity. The final diagnosis was uterine adenosarcoma with sarcomatous overgrowth, International Federation of Gynecology and Obstetrics stage IC. The patient received three cycles of adjuvant doxorubicin plus ifosfamide chemotherapy and remained free of recurrence 18 months after surgery. This case highlights the diagnostic value of hysteroscopic polypectomy in patients with intracavitary uterine lesions and underscores the importance of careful histopathological evaluation for the early recognition of sarcomatous overgrowth.