Primary ovarian leiomyoma is a rare tumor and accounts for only 0.5% to 1% of all benign ovarian tumors 1. Lipoleiomyoma is even rarer, limited to only 4 case reports in the English literature 2–5. The first case of ovarian lipoleiomyoma was reported in 1989 by Dodd et al. 2 Lipoleiomyoma is composed of benign smooth muscles admixed with adipose tissue. We, hereby, describe 1 rare case report of ovarian lipoleiomyoma in a 57-yr-old woman.
A 57-yr-old woman presented with upper abdominal pain for one and half months. She previously went vaginal hysterectomy without bilateral salpingo-oophorectomy 20 yr earlier in view of uterine prolapse and fibroid, although the histopathologic report was not available. She underwent hemorrhoidectomy almost at the same time 19 yr earlier. She was para 2 with 2 full-term vaginal deliveries at home and last gave birth 30 yr earlier. She had no history of loss of weight/appetite, no foul smelling vaginal discharge, and no burning micturition. She was a known hypertensive patient on treatment since 34 yr and was recently found to have an increased fasting glucose level of 140 mg/dL; she was started on an antiglycemic agent 1 mo earlier. She was a diagnosed and treated case of multiple sclerosis. On examination, she was afebrile with normal respiratory rate with controlled hypertension. Abdomen was soft, nontender. No organomegaly was seen. Respiratory and cardiovascular examination was normal. Per speculum examination revealed normal vault and vagina. No mass was felt through vault. No tenderness was elicited. Contrast-enhanced computed tomographic examination revealed a 60×54×56 mm heterogenous attenuation, nonenhancing in the left adnexa, and inseparable from the left ovary (Fig. 1). This lesion showed fat and soft tissue attenuation with no abnormal calcification. It had well-defined margins with normal fat planes with urinary bladder, small and large bowel, and pelvic side walls. The radiologic impression was of dermoid cyst/teratoma. Her hemogram findings, renal function test, and liver function test were normal. Viral markers were negative. Electrocardiogram and chest x-ray were normal. Urine culture was sterile. CA-125 level was 6 U/mL. Thyroid function test was normal.
Subsequently, the patient underwent exploratory laparotomy with bilateral salpingo-oophorectomy. Intraoperatively, a left-sided ovarian mass measuring 5×4×4 cm was identified. No adhesions were found, as described in surgical procedure notes. Contralateral ovary and fallopian were normal. The postoperative period of the patient was uneventful, and she was discharged after 5 d. The specimen was sent for histopathologic examination. The left ovarian mass measured 5×4×4 cm. The external surface was smooth. The cut surface was solid, homogenous, and gray white with few fatty areas. No cystic components were seen. No hair, bone, cartilage, or any sebaceous material was identified. Microscopic examination revealed long and short fascicles of smooth muscles with intervening areas of hyalinization and edema (Fig. 2). Scattered islands of adipose tissue as well as singly scattered adipocytes intermixed with these areas were seen (Fig. 3). The smooth muscle cells were spindle-shaped and had elongated cigar-shaped nuclei and abundant eosinophilic cytoplasm. No significant atypia, mitosis, or necrosis was seen (Fig. 4). A total of 8 sections were taken and carefully examined to rule out dermoid cyst. No teratomatous components were noted. No evidence of endometriosis was noted in either ovary. Immunohistochemistry was carried out, and the tumor cells showed strong cytoplasmic positivity for caldesmon, desmin, estrogen receptor, and progesterone receptor (Fig. 5). These cells were negative for inhibin, calretinin, and CD10, except for occasional positive cells, which may be luteinized stromal cells.
Benign lipomatous tumors in the ovary are very rare and include lipoma, lipoleiomyoma, and teratoma, with a prominent adipose tissue component. Lipoma is characterized by adipose tissue only with the absence of smooth muscles. However, teratomas usually have components derived from different germ layers and are usually easily excluded. Adipose tissue may be a part of liposarcomatous areas of the malignant mixed mullerian tumor. However, the marked atypia of the tumor cells and the presence of lipoblasts distinguish this tumor from benign lipoleiomyomas.
Primary ovarian lipoleiomyoma is an extremely rare tumor. Microscopically, these tumors are similar to leiomyoma with inclusion of adipocytes. Normally, adipose tissue and smooth muscles are not a component of ovarian parenchyma, except in the wall of arterial vessels in ovarian stroma. It has been hypothesized that primary ovarian leiomyoma arises from these smooth muscles; however, precise histogenesis is unknown. The presence of adipose tissue in lipoleiomyoma is even more intriguing and uncertain. Various hypotheses for their presence have been proposed. One hypothesis is that of adipose prosoplasia proposed by Hart and Abell 6. According to them, ovarian stromal cells and mesenchymal cells have multipotentiality and can differentiate into adipose tissue 6. Other proposed theories include metaplastic differentiation of smooth muscle cells into adipose tissue, misplaced embryonic rests, infiltration of parametrical adipose tissue, traumatic implantation, and entrapment of adipocytes from surrounding tissues within the inclusion cysts 2–5. Kelekci et al. 7 in 2015 described simultaneous existence of uterine lipoleiomyoma and ovarian leiomyoma. This study further supports the fact that development of lipoleiomyoma may be a result of metaplastic transformation of smooth muscle into adipose tissue in a long-standing case of leiomyoma.
The diagnosis of ovarian lipoleiomyoma was being made in this case on the basis of characteristic histologic features, along with computed tomographic scan features showing enlarged left adnexal with nonvisualized left ovary, an almost total replacement of ovarian parenchyma by the tumor. Moreover, the patient had a history of having undergone a hysterectomy 20 yr earlier. Almost all of the ovarian lipoleiomyoma are reported in patients who are in their 50s and 60s, including that of our case. Table 1 summarizes the clinical profile of the reported cases of these tumors. These tumors present with gradually progressive abdominopelvic mass related to location and size of tumor. One case presented with postmenopausal spotting. The size of these tumors ranges from 6 cm to the largest one measuring 26 cm. The ovarian leiomyoma, in contrast, occurs over a wide age range including adolescence. Moreover, many of these leiomyomas are small and only occasionally are very large 8. The late presentation of lipoleiomyoma might be possibly related to metaplastic adipose tissue formation in long-standing silent cases of ovarian leiomyoma.
Lipoleiomyoma of the ovary is an extremely rare tumor. These tumors are restricted to elderly adult women and present as pelvic mass or abdominal pain. Histologically, the presence of fat in the ovarian parenchyma would be worrisome. However, it is restricted to a limited number of diagnoses including benign entities like lipoma, lipoleiomyoma, teratoma, or malignant neoplasm. Liposarcoma occurs primarily or as part of sarcomatous transformation in mixed carcinoma. These lesions can be easily differentiated on the basis of clinical and histologic grounds.
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Keywords:©2019International Society of Gynecological Pathologists
Lipoleiomyoma; Ovary; Adipocytic lesions