A huge lipoleiomyoma of uterus: A Case Report and Review of Literature

Lipomatous uterine tumors are unusual benign neoplasms1. The reported incidence varies from 0.030.2%2.These tumors usually occur in obese perimenopausal and post menopausal women between 50 and 75 years of age. 90% of these patients are older than 40 years of age3. Histologically, lipoleiomyoma is composed of an intimate admixture of mature adipocytes and smooth muscle cells. It is mitotically inactive. The term lipoleiomyoma covers a spectrum of lesions with a fat content that ranges from being a minor component in what is otherwise a leiomyoma to being a neoplasm composed of entirely of mature adipocytes4.


Introduction
Lipomatous uterine tumors are unusual benign neoplasms 1 . The reported incidence varies from 0.03-0.2% 2 .These tumors usually occur in obese perimenopausal and post menopausal women between 50 and 75 years of age. 90% of these patients are older than 40 years of age 3 . Histologically, lipoleiomyoma is composed of an intimate admixture of mature adipocytes and smooth muscle cells. It is mitotically inactive. The term lipoleiomyoma covers a spectrum of lesions with a fat content that ranges from being a minor component in what is otherwise a leiomyoma to being a neoplasm composed of entirely of mature adipocytes 4 .

Case Report
A 60 year old female patient presented with complains of abdominal fullness and enlargement for approximately 10years. The Patient was a known case of hypertension with left sided hemiparesis due to right MCA (Middle Cerebral Artery) haemorrhagic infarct which was diagnosed in 2008. No antecedent significant history was elicited. Per abdominal examination revealed enlarged abdomen approximately 32-34 weeks' size. Swelling was firm in consistency. The overlying skin was stretched.
General physical examination was unremarkable except generalized atrophy of left upper limb and none of the peripheral (eg. axillary & inguinal) lymphnodes were palpable.
Complete haemogram and blood biochemistry reports were within normal limits except for the fasting and post prandial blood sugar which remained persistently high during the course of admission. Therefore patient was put on antidiabetic treatment. Ultrasonography revealed a 31X31cm sized heterogenous, hypoechoic lesion involving whole IJBR (2013) 04 (02) www.ssjournals.com

Abstract
Lipoleiomyoma is known to be an extremely rare benign tumor of uterus and is suspected to be a variant of leiomyoma. Apart from uterus, it can also occur in different locations including cervix and ovaries. The typical signs and symptoms of lipoleiomyoma are quite similar to that of leiomyoma. Here we report a case of lipoleiomyoma of uterus in a 62 years old female patient with complain of abdominal enlargement and fullness. It is aimed to discuss the morphological characteristics and differential diagnosis of lipoleiomyoma. In this case preoperative presumptive diagnosis of a large leiomyoma was made by assessing the computed tomography (CT) images and the final diagnosis of lipoleiomyoma was confirmed histopathologically. Keywords:Lipoleiomyoma, tumor, benign, uterus, CT (Computed Tomography) scan abdomen and pelvis. Uterus was not seen separately from the lesion.
CT scan of abdomen with pelvis revealed 23x22x15cm sized well defined large heterogeneously enhancing lesion with presence of fat density within it arising from the pelvis and reaching up to umbilical region and occupying bilateral iliac fossa, lumbar region, hypogastric and umbilical region. Other findings were unremarkable.

Image.1,2: CT Scan
Pan hysterectomy was done via an abdominal vertical incision approach and a huge mass involving whole of the uterus was seen. The specimen was sent for histopathological examination.

Pathological Examination
Gross examination revealed uterus and cervix measuring 30x28x20cm and weighing 12kg. On cut section endometrial cavity is not identified and is replaced by a tumor with whirling appearance with areas of fat within.

Image:3. Gross appearance
Microscopic examination revealed admixture of smooth muscle and mature adipose tissue. It shows whorling and interlacing bundles of smooth muscle cells separated by vascularized connective tissue. Nuclei are spindly ovoid. No nuclear atypia or significant mitoses is seen. Marked mature adipose tissue intermixed with smooth muscle are evident.

Discussion
Uterine lipoleiomyoma is a rare mesenchymal neoplasm and mostly described as a variant of uterine leiomyoma. Since Lobstein's first description of lipoleiomyoma in 1816, approximately 180 cases have been reported in the literature 5 .The other nomenclatures' for this tumor are fibrolipoleiomyoma, benign mixed mesodermal tumor, lipomatous tumor and so on 6 . Since most cases are not referred due to their benign behavior and also in most circumstances the fat component represents a more or less abundant adipose cell population in the context of common leiomyoma of the uterus, their precise incidence is unknown. Many of these patients are asymptomatic, but in some patients symptoms are similar to those of uterine leiomyomas, such as pelvic discomfort, heaviness and pressure or vaginal bleeding. www.ssjournals.com vessels strengthen the neometaplasia of pericapillary pluripotential mesencyhmal cells as suggested by Sieinski and Resta et al. 7 In all cases, variable degrees of vimentin and desmin positivity in mature adipocytes might suggest a direct transformation of muscle cells into adipose cells. All the adipose cells were negative for HMB-45 antigen. Thus immunohistochemical findings suggest a complex histogenesis for these tumors, which may arise from perivascular immature mesenchymal cells or direct transformation of smooth muscle cells in to adipocytes by means of progressive intracellular storage of lipids 10,11 .
Histolopathologically, three types of uterine tumors with lipomatous component are seen 12 : a) Pure lipoma consisting of adipocytes and very few scattered smooth muscle cells, b) Lipoleiomyoma with a variable amount and distribution of adipocytes and smooth muscle cells, c) Angiomyolipoma with prominent vascular structures admixed with adipocytes and smooth muscle cells.
Though imaging plays an important role in preoperative diagnosis and localization of the lipoleiomyoma, it is the final histopathological examination that confirms the diagnosis.
The differential diagnosis of the lipomatous mass in the pelvis includes benign cystic teratoma, malignant degeneration of cystic teratoma, non-teratomatous lipomatous ovarian tumor, benign pelvic lipomas, liposarcomas and lipoblastic lymphadenopathy. Association of lipomatous uterine tumors and endometrial carcinomas with lipoleiomyosarcoma 13 arising in uterine lipoleiomyomas has been reported. Lipoleiomyomas when asymptomatic require no treatment and are clinically similar to leiomyomas. So, it is important to differentiate these tumors from ovarian teratoma, which requires surgical excision. Lipoleiomyomas are benign tumors of the uterus that do not affect mortality (14) .
In summary, lipoleiomyoma is an extremely rare benign tumor of uterus and it is believed to be a variant of leiomyoma. Lipoleiomyomas when asymptomatic require no treatment and are clinically similar to leiomyomas. Patients having lipoleiomyomas are often overweight and menopausal.