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There are only two published case reports of lipoleiomyoma in the English literature. We report a case of lipoleiomyoma of the ovary in a woman who was in her fifties. She presented with a gradually progressive abdominal mass of 8 months duration. Abdominal imaging showed a large mass that was fed by right ovarian pedicle. Right ovary was not visualised. The excised mass was nodular and encapsulated; the cut section was yellowish with scant grey–white whorled areas. Microsections showed a mature adipose tissue admixed with leiomyomatous areas without cellular atypia and adjacent compressed ovarian tissue. Immunohistochemical staining showed diffuse positive reaction for desmin confirming that spindle cells were smooth muscle cells. A diagnosis of lipoleiomyoma of the ovary was made based on the radiological, histopathological and immunohistochemical findings.
Primary leiomyoma is a rare tumour of the ovary.1 Lipoleiomyoma of the ovary is even more uncommon. There are only two published case reports of lipoleiomyoma of the ovary in the English language literature.2,3 We report here a case of primary lipoleiomyoma of the ovary because of its rarity. It can also be occasionally misdiagnosed as sarcoma on clinical and radiological examination.
A woman in her fifties presented with a gradually progressive abdominal mass of 8 months duration. Abdominal CT and ultrasound scan revealed a large mass suspected to be a liposarcoma. The CT scan demonstrated a huge fat density in the right adnexa with few solid enhancing components and minimal fluid. The right ovary was not visualised separately but the right ovarian pedicle was feeding the mass. The ultrasound scan showed a large intraperitoneal echogenic mass with hypoechoic areas and fluid pockets. The uterus was normal in size and had no fibroids in both the scans.
The mass weighed 4.5 kg and comprised of four well‐encapsulated nodules attached to one another. Three nodules were large and each measured approximately 18×15×12 cm. A fourth central small grey‐white nodular mass measured 4×2×2 cm. Cut sections of the two large nodules showed uniform yellow lobules; the third large nodule was also yellowish but had a central grey‐white whorled mass that measured 6 cm across (fig 11).). The cut section of the small nodule had a whorled appearance. One of the nodules had a pearly white area on the external surface suggestive of a compressed ovary.
Multiple representative sections from the smaller central nodule and the grey‐white area in one of the larger nodules showed a tumour comprising predominantly smooth muscle cells arranged in interlacing fascicles admixed with small foci of mature adipose cells (fig 22).). The sections from the large yellowish masses showed extensive mature adipose tissue in the form of lobules separated by thin fibrovascular septae. Intimately admixed with these adipose lobules were multiple leiomyomatous areas (fig 33).). Stroma showed scattered lymphocytes, plasma cells and eosinophils. Also seen were focal areas of hyaline degeneration. Sections from the pearly white area showed compressed ovarian stroma with few adipose cells. To confirm that spindle cells were smooth muscle cells, immunohistochemistry was performed using desmin, which showed a diffuse positive reaction (fig 44).
Primary leiomyoma of the ovary is uncommon and they account for about 1% of the benign neoplasms.4 Lipoleiomyoma is even rarer. To the best of our knowledge, this is the third case reported.
We made a diagnosis of lipoleiomyoma of the ovary based on the presence of intimately admixed mature fat and smooth muscle cells. It was considered to be of ovarian origin based on 1) the presence of ovarian tissue closely adherent to the excided mass, 2) presence of adipose tissue within the ovary and 3) CT scan showing the right ovarian pedicle feeding the mass and non‐visualisation of the right ovary.
Microscopic features are similar to leiomyoma, but in addition they have mature adipose tissue. The amount of fat may range from being a minor component in what is otherwise leiomyoma to being a neoplasm composed entirely of mature adipocytes.5 Primary ovarian leiomyoma most likely originates from smooth muscle cells in the walls of the arterial vessels within the cortical stroma, corpus luteum and in the ovarian ligaments at their point of attachment to the ovary.6 Its precise histiogenesis is, however, uncertain.7 The theories on histiogenesis of adipose tissue are unresolved even in the case of the uterus where these tumours are relatively more common than in the ovary. In uterine origin, they most probably represent tumour metaplasia within a leiomyoma.5,8 In ovary too, presence of adipose tissue might represent metaplasia.
Fatty tumours of the ovary are very rare and almost invariably benign.4 The tumours are usually found in menopausal and post‐menopausal women. Clinically, the tumours are asymptomatic and discovered either incidentally or when they attain huge sizes with attendant complications. The only puzzle for the pathologists could be the unexpected presence of fat in the ovary. Occasionally, the clinical presentation and macroscopic appearance may mimic sarcoma, as in this case, and create diagnostic confusion.3 Primary leiomyoma must also be differentiated from pedunculated subserosal parasitic uterine leiomyoma, which has lost its attachment from the uterus and is instead attached to the ovary.9 Lastly, it should be differentiated from ovarian fibroma, which is more common.9
Competing interests: None.