A non-infiltrating, benign mesenchymal neoplasm arising from the uterine corpus. It is characterized by the presence of neoplastic cells that resemble the cells of the proliferative phase of endometrial stroma and numerous thin-walled small vessels. It usually presents with abnormal uterine bleeding and menorrhagia. The disease is EFO_1000241 (Endometrial Stromal Nodule).