Diffuse uterine lipoleiomyomatosis

A 55-year-old postmenopausal woman (G2P2) seeks care due to experiencing increasing pelvic pressure and urinary incontinence over the past three months. No uterine bleeding was reported. Upon physical examination, only a slight abdominal distention is noted, with no discomfort upon palpation. Gynaecological examination of the vagina and cervix was unremarkable. No relevant personal or family medical history.

Transabdominal (Figure 1) and transvaginal ultrasound (US) showed a large, lobulated, hyperechoic mass with a partially hypoechoic rim and posterior acoustic attenuation, measuring 8x6 cm. This lesion originated from the myometrium and exhibited an extrauterine component.

Subsequently, a pelvic computed tomography (CT) scan (Figures 2a, 2b and 2c) was conducted, uncovering multiple uterine masses originating from the corpus, some with extrauterine extension. These masses presented a composition characterised by soft tissue densities and a lower attenuation component, indicative of the presence of macroscopic fat.

To further characterise these findings, a pelvic magnetic resonance (MR) was performed. MR demonstrated an enlarged and lobulated uterus with well-defined masses located in the posterior and right paralateral aspects of the uterine corpus (Figure 3a). In T1-weighted images, these masses displayed central areas of high signal intensity, transitioning to hypointensity in fat-saturated sequences (Figure 3b). Notably, the lesions did not exhibit restricted diffusion (Figure 3c), and the soft-tissue component demonstrated strong and heterogeneous enhancement following gadolinium-based contrast administration (Figure 3d).

Both ovaries were identified without evidence of expansive lesions.

Background

Uterine lipoleiomyomas, a rare benign neoplasm, are composed of varying proportions of adipose tissue and smooth muscle cells. Their reported incidence ranges from 0.03% to 0.2%, predominantly affecting postmenopausal women [1]. Unlike leiomyomas, lipoleiomyomas continue to grow after menopause despite the absence of circulating estrogen [2].

Clinical Perspective

Although the majority of patients remain asymptomatic, some may exhibit symptoms similar to those associated with typical leiomyomas of equivalent size and location. Frequently observed clinical manifestations include abnormal uterine bleeding, abdominal/pelvic pain, palpable mass, urinary frequency/incontinence, and a sensation of pressure [3].

Imaging Perspective

Transvaginal US typically serves as the initial imaging modality, with the identification of a hyperechoic uterine mass potentially suggesting the diagnosis. However, MR assumes a crucial role in achieving accurate tissue characterisation and differential diagnosis. Due to the prevailing fatty component, hyperintensity is seen on T1-weighted sequences, accompanied by the presence of chemical shift artefacts. Additionally, fat suppression techniques prove beneficial in confirming the diagnosis [4].

The differential diagnosis for a uterine fat-containing lesion includes benign entities such as pure lipoma, lipoleiomyoma, angiomyolipoma, fibromyolipoma, and malignant neoplasm such as liposarcoma or carcinosarcoma with liposarcomatous differentiation [4]. Distinguishing between a lipoleiomyoma and lesions requiring excision is crucial but often poses diagnostic challenges.

Outcome

Lipoleiomyoma generally carries a favourable prognosis and can rarely progress to leiomyosarcoma. Treatment protocols align with those for uterine leiomyomas, and surgical intervention is generally not recommended for asymptomatic patients [2].

In our case, the conjunction of clinical symptoms, imaging features suggestive of potential malignancy, and subsequent discussion in multidisciplinary reunion, surgical intervention was deemed necessary. A laparoscopic procedure involving radical hysterectomy and bilateral salpingo-oophorectomy was performed, with an uneventful course.

The anatomopathological study revealed the diagnosis of uterine lipoleiomyomatosis with intravascular involvement of the uterine corpus vessels. This is an exceedingly rare manifestation associated with leiomyomas and lipoleiomyomas, which represents an aggressive intravenous growth into intra- and extra-uterine veins [5]. Notably, the intravascular component was only identified through the histological analysis of the surgical specimen, as it was not depicted in the imaging examinations.

Take Home Messages

• Most commonly observed in post-menopausal women with a clinical presentation that resembles symptomatic leiomyomas.
• An ultrasound revealing a hyperechoic mass with a partially hypoechoic rim may suggest the diagnosis.
• MR plays an important role with T1-weighted sequences, fat suppression techniques, and chemical shift imaging to detect intralesional fat, thereby aiding in accurate diagnosis.

Written informed patient consent for publication has been obtained.