Abdominal Imaging

ª Springer-Verlag New York, Inc. 2004 Received: 22 January 2004 / Accepted: 18 February 2004 / Published online: 8 June 2004

Abdom Imaging (2005) 30:117–119 DOI: 10.1007/s00261-004-0202-7

Bilateral ovarian leiomyomas: CT and MRI features T. Yoshitake,1 Y. Asayama,1 K. Yoshimitsu,1 H. Irie,1 H. Aibe,1 T. Tajima,1 A. Nishie,1 T. Nakayama,1 D. Kakihara,1 K. Ariyoshi,2 E. Kaneki,3 H. Honda1 1

Department of Clinical Radiology, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan Department of Gynecology and Obstetrics, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan 3 Department of Anatomic Pathology, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan 2

Abstract We recently treated a 21-year-old woman with leiomyomas arising from the bilateral ovaries, a very rare condition. On magnetic resonance imaging, more than half of the left adnexal mass showed low signal intensity on T2-weighted images and good enhancement by gadolinium-DTPA, and the remaining part showed high signal intensity on T2-weighted images and no enhancement. The right adnexal mass showed homogeneously low signal intensity on T2-weighted images, so the lesions initially were diagnosed as ovarian fibromas or as thecomas with a certain degree of degeneration. Pathologic examination of the excised tumors proved that they were bilateral ovarian leiomyomas; in addition, the tumor from the left side showed hemorrhagic and myxoid changes with torsion of 180 degrees. Key words: Ovary—Leiomyoma—CT—MRI

Ovarian masses with fibrous components include fibroma, fibrothecoma, cystadenofibroma, and Brenner tumor. These fibrous components tend to show low signal intensity on T2-weighted imaging. Troiano et al. [1] demonstrated that predominant low signal intensity on T2-weighted images is a diagnostic finding of fibroma and fibrothecoma. We recently treated a case of leiomyomas of the bilateral ovaries, rare benign ovarian tumors, that initially were diagnosed as fibromas or thecomas of the bilateral ovaries due to their signal intensity on T2-weighted magnetic resonance (MR) images. We describe the radiologic findings of these rare tumors and review the literature. Correspondence to: Y. Asayama; email: [email protected]. ac.jp

Case report A 21-year-old unmarried woman (gravida 0, para 0) had felt lower abdominal distention for 2 months and lower abdominal discomfort for a few months and consulted the local clinic due to the gradually increasing intensity of lower abdominal pain. Abdominal sonography showed lower abdominal masses, and she was referred to the gynecology department of our hospital. Pelvic examination revealed two large hard masses abutting the normal uterus, and the mass on the left side of the uterus was found to cause tenderness. The patient’s serum C-reactive protein level was elevated at 7.22 mg/dL and her serum carbohydrate antigen 125 (CA125) level was 149.9 U/mL (normal < 35 U/mL). Other laboratory findings such as white blood cell count, carcinoembryonic antigen, a-fetoprotein, human chorionic gonadotropin, and estradiol were within normal limits. Pelvic sonography depicted a normal uterus and two large solid masses, one on each side of the uterus. Contrast-enhanced computerized tomography (CT) showed a 10-cm dumbbell-shaped mass superior to the uterus and a 7-cm mass posterior to the uterus; the former was primarily cystic and consisted of two differently enhancing components, and the latter was almost solid and showed delayed enhancement from the peripheral area. On T2-weighted MR imaging (MRI), the mass superior to the uterus showed heterogeneous signal intensity, with most of the mass showing high signal intensity and part of it showing low intensity, whereas the mass posterior to the uterus showed homogeneous low signal intensity (Fig. 1A). These masses abutted the uterus but were well circumscribed and sharply demarcated from the uterus and showed no evidence of the beak sign or a flow void between the masses and the uterus. On postcontrast T1-weighted imaging, the T2-prolonged area of the superior mass showed poor enhancement, whereas the

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Fig. 1. A MRI depicts two large masses at the superior and posterior sides of the uterus. The mass superior to the uterus shows heterogeneous signal intensity, with most of the mass showing high signal intensity and part showing low signal intensity (white arrow). The mass posterior to the uterus has homogeneous low signal intensity on T2-weighted image (black arrow). These masses abut the uterus, but there is no evidence of the beak sign or a flow void between the masses and the uterus. B On postcontrast T1-weighted image, the

T2-prolonged area of the superior mass shows poor enhancement (white arrow) and the T2-shortened areas of the superior mass (arrowhead) and the posterior mass (black arrow) have good enhancement. C Axial T2-weighted image reveals two cystic structures abutting the masses, which we identified as the compressed and deformed bilateral ovaries. The posterior mass appears to arise from the right ovary (black arrow) and the superior mass from the left ovary (white arrow)

T2-shortened areas of the superior mass and the posterior mass showed good enhancement (Fig. 1B). Axial T2-weighted images displayed two cystic structures abutting these masses. We identified these as the compressed and deformed bilateral ovaries, with the posterior mass arising from the right ovary and the superior mass from the left ovary (Fig. 1C). The vessels that seemed to be bilateral gonadal veins continued to the masses (not shown). A small amount of ascetic fluid was noted. There was no significant lymphadenopathy and no findings suggesting leiomyomatosis peritonealis disseminata or intravenous leiomyomatosis. Our final radiologic diagnosis was bilateral ovarian fibroma or thecoma, due to the discriminative signal intensity on T2-weighted images and the T2-prolonged area of the superior mass, which was deemed to be indicative of degenerative change. Because the patient’s abdominal pain did not improve, operation was performed. Exploration through a midline incision revealed a small amount of serous bloody ascites and bilateral, irregular, solid ovarian tumors. The right ovarian tumor was solid and measured 8 9 6 9 6 cm, with a smooth, hard, elastic, white surface. The left ovarian tumor had a similar surface, was solid, and measured 12 9 10 9 7 cm, but also appeared to have hemorrhagic change with a torsion of 180 degrees. The uterus and fallopian tubes appeared completely normal. There was no evidence of intraperitoneal carcinomatosis or other abdominal or pelvic pathology. Intraoperative histologic diagnosis showed no malignancy, and these two tumors were excised with preservation of normal ovarian tissue. Pathologically, the bilateral ovarian solid tumors were composed of interlacing bundles of spindle cells

with collagen fiber; in addition, the left ovarian tumor showed hemorrhagic and myxoid changes (Fig. 2A). Immunohistochemically, the spindle cells were positive on an a-smooth muscle actin stain (monoclonal; Sigma Chemical Co., St. Louis, MO, USA; Fig. 2B). The final histologic diagnosis was leiomyomas arising from the bilateral ovaries.

Discussion Primary leiomyoma of the ovary is a rare benign ovarian tumor and is usually found incidentally on routine pelvic examination at surgery or autopsy [2]. To our knowledge, approximately 70 cases have been reported in the international literature [1–8]. The ages of the patients in the reported cases ranged from 20 to 65 years, and approximately 17% of cases occurred after menopause [1–7]. This tumor is typically unilateral and small, generally smaller than 5cm in diameter [2, 3]. To the best of our knowledge, only two cases of bilateral ovarian leiomyomas have been reported in the international literature [4, 5]. Most cases are asymptomatic or present with only mild complaints of lower abdominal pain, but tumors sometimes become large enough to cause pelvic pain and increased abdominal girth [2, 3, 5, 6]. Acute symptoms due to torsion or necrosis, hydroureteronephrosis due to the large size of the tumor, or ascites are also possible [2, 7]. No specific symptoms of this tumor have been reported in the literature. In the present case, our patients CA125 level was elevated, however this is not considered a specific symptom because elevated CA125 may occur in many pelvic diseases [2].

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Fig. 2. A Pathologically, the bilateral ovarian solid tumors are composed of interlacing bundles of spindle cells with collagen fiber, and the T2-prolonged area of the left ovarian tumor shows myxoid change. B Immunohistochemically, the

spindle cells are positive on an a-smooth muscle actin stain. The final histologic diagnosis was leiomyomas arising from the bilateral ovaries

The most plausible theory is that leiomyomas arise from the smooth muscle of the walls of ovarian blood vessels [3]. Nevertheless, smooth muscle within the ovary has been identified by special stains in the ovarian follicles, in blood vessels of the cortical stroma, and in the ovarian ligaments, and to date, there has been no firm evidence for this hypothesis; histogenesis remains controversial [6, 9]. Ovarian leiomyoma is identical to uterine leiomyoma macroscopically and microscopically [6]. Most ovarian leiomyomas are solid, but secondary degeneration such as hyalinization, hemorrhage, calcification, and cyst formation may occur to some degree, as in the case of uterine leiomyomas [3, 5, 6, 8]. In the present case, part of the left ovarian leiomyoma showed myxoid change, but we believe that there was no correlation between the myxoid change and the torsion. Imaging features of primary ovarian leiomyoma have seldom been described in the literature [8, 10]. Kobayashi et al. [10] were the first to describe the MRI findings of ovarian leiomyoma. In their case, the tumor showed a wellcircumscribed hypointense mass on T1- and T2-weighted MR images and was sharply demarcated from the uterus, suggesting an ovarian tumor with fibrous tissue such as fibroma. Troiano et al. [1] also stated that predominantly low signal intensity on T2-weighted MRI is relatively specific for ovarian fibroma or fibrothecoma. Neither the existence of degeneration nor the degree of enhancement by gadolinium-DTPA is thought to be suggestive. In the present case, the presence of two compressed ovarian structures and the continuity of the bilateral gonadal vein to the masses indicated that these tumors arose from the bilateral ovaries. Thus, our diagnosis based on the signal intensity on T2-weighted imaging was ovarian fibroma or fibrothecoma. Ovarian leiomyoma is difficult to differentiate from fibroma or fibrothecoma. Okizuka et al. [11] described how secondary degeneration of uterine leiomyoma changes signal intensity on T2-weighted and gadolinium-DTPA–enhanced imaging. In the present case, the area without pathologic

degeneration showed low signal intensity on T2-weighted imaging and had good enhancement, and the area with myxoid degeneration showed high signal intensity and had poor enhancement. This result is consistent with the findings of Okizuka et al., so we assume that the signal intensity of ovarian leiomyomas can vary as in the uterus. In conclusion, we describe a rare case of bilateral ovarian leiomyomas. If low signal intensity on T2weighted images is recognized in ovarian tumors, not only fibroma or fibrothecma but also ovarian leiomyoma should be considered. In addition, the signal intensity differed in the right and the left tumors due to differing degrees of degeneration that were proved pathologically. This interesting difference in intensity is described here for the first time in relation to ovarian leiomyoma.

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