Abstract

Lipoleiomyoma is a rare benign uterine tumour consisting of smooth muscles and mature adipose tissue.1 The origin of lipomatous lesions of the uterus has been the subject of much speculation.2 Most cases of lipoleiomyoma cannot be distinguished clinically from leiomyoma. The diagnosis is made only after the study of surgically removed specimen. Most of the diagnosis can be made on the typical gross appearance of the tumour.2

Introduction

Lipoleiomyoma is a rare benign uterine tumour consisting of smooth muscles and mature adipose tissue. In various literature searches done of lipomatous tumour of the uterus, the incidence has been found to be 0.14%.3 Most of the patients are postmenopausal, predominantly in their fifties and sixties. The size ranges from several millimetres to 32 cms in diameter. They are soft and yellow in colour. Clinically the symptoms are indistinguishable from those of ordinary fibroid.

In literature search; association of lipoleiomyoma with high incidence of gallbladder disease has been seen.4 We present one such case of lipoleiomyoma of the uterus along with chronic cholecystitis in a 60 year old postmenopausal lady.

Case Report

Our patient was a 60 year old lady, who presented with a chief complaints of vomiting, loose motions, and a palpable lump in the abdomen since 15 days. Clinical examination revealed a firm non-tender hypogastric lump. USG examination of the abdomen showed a large mass arising from pelvis suggestive of 1) An uterine fibroid with fatty metamorphosis, 2) A large right ovarian dermoid. Also seen were gallbladder calculi and fatty infiltration of the liver.

CT scan of the abdomen revealed a large mass measuring 12 x 11 x 9.5 cm arising from the pelvis and showing predominantly fat density with enhancing rim of soft tissue (Fig. 1 arrow). Possibilities were 1) Uterine firoid with fatty degeneration and 2) right ovarian dermoid adherent to the uterine fundus.

Also there was evidence of mild hepatomegaly with fat infiltration and multiple gallbladder calculi.

Patient was taken up for exploratory laparotomy and a complete hysterectomy with bilateral salpingo-oophorectomy and cholecystectomy was performed.

Fig. 1 :CT Scan of the abdomen showing a large mass arising from the pelvis and showing predominantly fat density with enhancing rim of soft tissue (arrow).	Fig. 2 :The specimen of uterus showing a large deep yellow, soft intramural mass measuring 10 x 10 8 cms and compressing the uterine cavity. The mass was intersected by bands of greyish white fibrous tissue.	Fig. 3 :Microscopy of the uterine mass showed mainly lobules of mature adipose tissue separated by thin fibrous septae (100 X). Intermingled with the lobules were seen fascicles of smooth muscle cells. Inset to highlight adipocytes (400 X).

The specimen of uterus showed a large intramural mass measuring 10 x 10 x 8 cm and compressing the uterine cavity. The mass was deep yellow in colour, soft in consistency and intersected by bands of greyish white of fibrous tissue (Fig. 2). The gallbladder showed flattened mucosa and presence of multiple pigmented calculi.

Microscopy of the uterine mass showed mainly lobules of mature adipose tissue separated by thin fibrous septae. Also intermingled with the lobules were seen fascicles of smooth muscle cells (Fig. 3). Sections from the gallbladder showed features of chronic cholecystitis.

Discussion

Lipoleiomyoma is a rare neoplasm composed of an intimate admixture of mature adipocytes, smooth muscles and fibrous tissue. The incidence of this tumour varies between 0.03% to 0.2%. Most of the patients are postmenopausal predominantly in their fifties and sixties.3 Clinically the symptoms are indistinguishable from those of ordinary fibroids. The tumours are grossly rounded or oval, well encapsulated, yellow and soft. Histologically the tumour shows lobules of mature adipose tissue separated by bundles of smooth muscles and fibrous septae.2 There is much speculation on the histogenesis of uterine lipoleiomyomas because adipose tissue does not occur in the myometrium.2,5 The various theories advanced include misplaced embryonic fat cells, metaplasia of muscle or connective tissue, perivascular extension of fat along uterine vessels and origin from pleuripotent cells and embryonic multipotential component. Some others advocated the possibility that these growths are mixed tumours that arise from immature cells with multiple potentialities for differentiation. Salm suggested that these tumours should be considered as fatty metaplasia in leiomyoma. Another theory was that fat cells proliferate into the uterus from the subserosal fat of the neighbouring structures and also from perivascular fat cells accompanying the blood vessels into the uterus. In most of the cases the diagnosis is made on the gross appearance as these tumours have the typical yellow greasy appearance of adipose tissue with interlacing fibrous septate. At times gross appearance may suggest leiomyosarcoma, but mitotic activity (at least 5 mitotic figures per 10 hpf) on histology favours leiomyosarcoma.

References

1. Tshushima Y, Kita T, Yamamoto K. Uterine lipoleiomyoma: MRI, CT and Ultrasonographic findings. The British Journal of Radiology 1997; 70 : 1068-70.
2. Dharkar DD, Kraft JR, Gangadharam D. Uterine lipomas. Arch Pathol Lab Med 1981; 105 : 43-5.
3. Kauser LM, Carrasco CH, Sheehan CR, et al. Lipomatous tumour of the uterus: Radiographic and ultrasonic appearance. British Journal of Radiology 1979; 52 : 992-3.
4. Lin M, Hanai J. Atypical lipoleiomyoma of the uterus. Acta Pathol Jpn 1991; 41 (2) : 164-9.
5. Lipomas of the uterus. Am J Obst and Gynec 1957; 73 (6) : 1358-61.
6. Haines, Taylor. Obstetrical and Gynaecological Pathology. Fox H and Wells M. Churchill Livingstone. 4th edition, pg. 567-8.

*Associate Professor; **Resident; Department of Pathology, LTMMC and LTMGH, Sion, Mumbai - 400 022.