What are the clinical symptoms and uterine enlargement manifestations of intraventricular leiomyomatosis that differ from those of ordinary uterine fibroids? Intraventricular smooth muscle tumor (IVL) is a rare, histologically benign but biologically malignant tumor. It is in fact a very rare type of uterine fibroid, and the main characteristic of this type of fibroid is its growth into the veins. Depending on the site of involvement of the lesion, it is classified as intraventricular smooth muscle myomatosis, when the lesion is still confined to the uterus, or smooth muscle myomatosis with large vessel or cardiac involvement, when the lesion extends beyond the uterus to the iliac vein, the inferior vena cava or even the heart, which can be life-threatening in severe cases. The clinical symptoms are therefore related to the extent of lesion involvement. When the lesion is confined to the pelvic cavity, it manifests as lower abdominal pain, abdominal distension, and increased menstruation, which are similar to the symptoms of general uterine fibroids; when it compresses the ureter, it may cause symptoms of urinary tract obstruction; when it invades the inferior vena cava and causes inferior vena cava obstruction, it shows symptoms such as abdominal distension and lower limb edema, which are easily misdiagnosed as thrombosis; when it involves the right heart cavity, it manifests as respiratory distress and right heart insufficiency, which are easily misdiagnosed as cardiac mucinous tumor. The uterus may show enlargement during gynecological examination, which is difficult to distinguish from general fibroids. What is the correlation between this disease and previous history of uterine fibroids? There are two theories regarding the mechanism of intraventricular smooth muscle tumors: (1) origin of smooth muscle within the uterine vascular wall; and (2) proliferation of smooth muscle tumors originating from the uterus into the vascular lumen. So are intraventricular smooth muscle tumors associated with uterine fibroids? A clinical report states that of 33 patients diagnosed with intraventricular smooth muscle tumors, 25 of them also had uterine fibroids or a history of myomectomy. This suggests that the vast majority of patients had concurrent uterine fibroids or a past history of myomectomy. Thus, the disease is highly correlated with fibroids. What are the more characteristic features of ultrasonography as a more important adjunctive test in diagnosis? The ultrasound presentation varies depending on the extent of the lesion. (1) When the fibroid is confined to the pelvis, it is similar to fibroids. The tumor may be located between the muscle walls and is a single or multiple hypoechoic nodule with clear borders. When the peri-uterine veins are involved, the tumor may appear as hypoechoic occupancy on one or both sides of the uterus, single or multiple, or multiple nodules of different sizes, scattered or fused, with clear borders, regular or irregular morphology, located in the lumen, and rich or little blood flow signal can be seen in CDFI. (2) When the iliac vein and inferior vena cava are involved, in addition to the above pelvic manifestations, the lumen of the iliac vein and inferior vena cava is thickened and filled with hypoechoic tissue, and a little blood flow signal is seen in CDFI. (3) When the heart is involved, hypoechoic striated echoes can be seen in the right atrium and even the right ventricle, which are connected to the inferior vena cava and can continue to extend down to the pelvic veins. Once this type of disease occurs, it is relatively urgent, so what are the surgical approach, the extent of resection and the main intraoperative concerns? The clinical management of uterine IVL is closely related to its prognosis. Surgical excision of the tumor is the only means to treat the primary and metastatic lesions. In the former, the primary tumor and the tumor invading in the inferior vena cava/heart are completely removed at one time; in the latter, the tumor in the atrium and the upper part of the inferior vena cava is removed first, and then the uterus and the parametrial tissue and the tumor in the lower part of the inferior vena cava are removed electively. For IVL confined to the uterus, the extent of surgery can be determined by the patient’s age and fertility requirements. For patients without fertility requirements, total hysterectomy with bilateral adnexal resection is recommended, and the periuterine vessels should be carefully explored for involvement. In the case of intraventricular myomas at the time of resection, complete resection should be performed. Is there a problem of recurrence and what details need to be noted for follow-up? Intraventricular smooth muscle disease is prone to recurrence after treatment. It may occur later in other vasculature when the lesion does not extend beyond the uterus at the time of hysterectomy or when the lesion has been completely excised outside the uterus. Sometimes it occurs several years after hysterectomy. Recurrence is associated with retention of endogenous estrogen in the ovaries. Total hysterectomy, bilateral adnexal and extra-uterine tumor resection is advocated to reduce recurrence and improve prognosis. For IVL patients who cannot be clearly diagnosed before surgery, not found intraoperatively, and relying on postoperative pathology for diagnosis, long-term close follow-up, regular gynecological examination and review of ultrasound, and CT or MRI if necessary, are needed after surgery for early detection of recurrence and metastasis and timely treatment.