Endometrioma With Calcification Simulating a Dermoid on Sonography

Case Report Endometrioma With Calcification Simulating a Dermoid on Sonography Kiran A. Jain, MD Several investigators have explored the sonographic diagnostic criteria of endometriomas. Endometriomas have characteristic findings on sonography. Diffuse dispersion of low-level echoes within a cystic mass is thought to be the most useful diagnostic feature. Mais et al 1 documented sensitivity of 88% and specificity of 90% in differentiating endometriomas from other ovarian masses with endovaginal sonography. Patel et al 2 identified diffuse low-level internal echoes in 95% of endometriomas and 19% of nonendometriomas. The presence of multilocularity or hyperechoic wall foci further increased the possibility of a given mass being an endometrioma. 2 They postulated that these two findings would have the highest diagnostic value in distinguishing endometriomas from other adnexal masses. This report presents an unusual case in which a large cystic adnexal mass showed a fluid-fluid level and a large, discrete calcification. A sonographic diagnosis of a dermoid was made; however, it proved to be an endometrioma on magnetic resonance imaging (MRI), which was later confirmed with laparoscopic removal and a pathologic report. Case Report Abbreviations MRI, magnetic resonance imaging Received March 30, 2006, from the Department of Radiology, University of California Davis Medical Center, Sacramento, California USA. Revision requested April 13, 2006. Revised manuscript accepted for publication April 27, 2006. Address correspondence to Kiran A. Jain, MD, Department of Radiology, University of California Davis Medical Center, 4860 Y St, Suite 3100, Sacramento, CA 95817 USA. E-mail: kiran.jain@ucdmc.ucdavis.edu A 37-year-old nulliparous woman was found to have a right adnexal mass on bimanual gynecologic examination while being investigated for infertility. The patient had no abdominal or pelvic pain. Her menstrual cycles were regular, and she had no abnormal vaginal discharge. She had no dyspareunia. She had been healthy and had no other complaints. Her medical history was unremarkable. On physical examination, she was a well-developed female in no acute distress. She was afebrile with normal blood pressure and pulse rate. Laboratory values revealed normal blood count, blood urea nitrogen electrolyte, and urinalysis findings. Abdominal examination findings were normal. Bimanual pelvic examination showed a normal cervix and a small, mobile, nontender uterus. The left adnexa was normal; however, there was a palpable mass in the right adnexa. The patient was therefore referred for pelvic sonography. 2006 by the American Institute of Ultrasound in Medicine J Ultrasound Med 2006; 25:1237 1241 0278-4297/06/$3.50

Endometrioma With Calcification Simulating a Dermoid Pelvic sonography depicted a normal uterus and normal left ovary. In the right adnexa, there was a 4 3 3.5-cm mass, which showed enhanced through-transmission, and a fluidfluid level consisting of echogenic fluid layering with hypoechoic fluid. This was thought to be a fat-fluid level (Figure 1A). It also showed an 11- mm discrete calcification (Figure 1B). The mass was surrounded by normal-appearing ovarian parenchyma. These findings were thought to be diagnostic of a cystic teratoma. Magnetic resonance imaging was recommended for confirmation of the sonographic diagnosis because MRI is recommended to characterize complex masses for definitive diagnosis at our institution. Magnetic resonance imaging showed a normal uterus and normal left ovary containing physiologic follicles. There was a 4 3 3.5-cm mass in the right ovary. This mass showed high signal intensity on conventional and fat-suppressed T1-weighted images (Figure 2, A and B). High signal intensity was also seen on fat-suppressed T2- weighted images (Figure 2C). Bright signal intensity not suppressed by fat is indicative of blood products. Normal ovarian parenchyma was seen surrounding the mass on fat-suppressed T2-weighted images (Figure 2C). The calcification within the mass that was well visualized on sonography (Figure 1B), was seen as a focus with low signal intensity on all the MRI sequences (Figure 2, A D). A fluid-fluid level was seen in the mass, with partial shading indicative of old blood, on T2-weighted images (Figure 2, C and D). This fluid-fluid level did not show fat signal intensity on MRI and was determined to be related to old and new blood products. On MRI, this was not thought to be fat-fluid level. Thus, with analysis of the signal intensities on all the sequences, the mass was thought to be an endometrioma containing an unusual feature of a discrete calcification. The patient then had a laparoscopic removal of the mass. Histopathologic findings of the resected endometrioma revealed extensive fresh and old blood with hemosiderin-laden macrophages. The calcification was located in the fluid portion of the mass. There was no solid component in this cystic mass at histopathologic examination. A marblelike calcification fell out when the mass was cut open after removal. Discussion Although endometriomas can have variable sonographic appearances, certain sonographic criteria are useful in making a definitive diagnosis. Most experts 1,3 5 have agreed on one common sonographic feature of diffuse dispersion of low-level echoes within a cystic mass. Patel et al 2 addressed a set of features that would increase or decrease the likelihood ratio for the diagnosis of an endometrioma. Their findings confirm that Figure 1. A, Transverse transabdominal sonogram shows a fluid-fluid level (arrow) in a cystic mass and solid ovarian tissue of normal ovarian parenchyma (arrowheads). B, Coronal endovaginal sonogram shows a cystic mass filled with diffuse low-level internal echoes and a 1.1-cm calcification (calipers). A B 1238 J Ultrasound Med 2006; 25:1237 1241

Jain the presence of diffuse low-level internal echoes is the important feature that helps discriminate an endometrioma from other lesions; 95% of endometriomas exhibit diffuse low-level internal echoes. Demonstration of hyperechoic wall foci in a mass with low-level echoes and absence of neoplastic features was strongly predictive of an endometrioma. 2 Thirty-five percent of endometriomas in their series showed hyperechoic wall foci, Figure 2. A, Axial T1-weighted image without fat suppression shows a mass with high signal intensity (star) surrounded by a rim of normal ovarian parenchyma (arrows). The focus with low signal intensity (curved arrow) is due to a calcification. U indicates uterus. B, Axial T1-weighted image with fat suppression shows a mass with high signal intensity (star) surrounded by a rim of normal ovarian parenchyma (arrows). The mass remains high in signal intensity despite fat suppression, which is suggestive of blood products. The focus with low signal intensity (curved arrow) is due to a calcification. C, Axial T2-weighted fat-suppressed image shows a mass with high signal intensity in the right adnexa and a fluid-fluid level (arrowhead) corresponding to the sonogram in Figure 1A. A focus with low intensity (curved arrow) is identified within the mass (star). Normal right ovarian parenchyma containing physiologic cysts is shown (thin arrow). A normal left ovary with small follicles is also shown (thick arrow). D, Sagittal T2-weighted image without fat suppression shows a mass with high signal intensity and a fluid-fluid level (arrowhead) and a focus with low signal intensity (curved arrow). Also notice the slightly decreased signal intensity of the posterior fluid level due to shading of old blood. A B C D J Ultrasound Med 2006; 25:1237 1241 1239

Endometrioma With Calcification Simulating a Dermoid whereas only 6% of nonendometriomas did so. Their data indicate that a mass with low-level internal echoes, hyperechoic wall foci, and no neoplastic features is 32 times more likely to be an endometrioma than another adnexal mass. Generally endometriomas are not thought to contain fluid-fluid levels. However, endometriomas contain blood of different ages, which sometimes can appear as a fluid-fluid level on imaging studies. The observation missed on the initial sonographic examination was that the dependent layer in the fluid-fluid level was echogenic, which was due to the presence of echogenic blood. If this echogenic layer was fat, it would have been in the supernatant location; that is, the mass would show supernatant hyperechoic and dependent hypoechoic layers. However, this mass showed supernatant hypoechoic and dependent hyperechoic layers, which have been observed in endometriomas. 6 Certain sonographic features (focal acoustic impedance, regional bright echoes, and hyperechoic lines and dots) are predictive of cystic teratomas. 7 Although the hyperechoic shadowing focus is very predictive of a teratoma, not all hyperechoic shadowing areas are due to calcifications. Furthermore, although a calcification can certainly occur in a teratoma, a calcification by itself is not pathognomonic of a teratoma. A teratoma can contain a nonshadowing echogenic focus or a shadowing calcification. The positive predictive value for individual sonographic features associated with dermoid masses is 80% for a shadowing echogenic focus and 20% for a fluidfluid level. 6 On sonography, the dermoid plugs are seen as an echogenic mass, often associated with distal acoustic shadowing. 8 Although hyperechoic foci are described in the wall of the endometriomas, a discrete shadowing focus similar to that seen in a dermoid cyst has not been reported in the literature. Histopathologic findings of the resected endometrioma revealed extensive fresh and old blood with hemosiderin-laden macrophages. A large, marblelike calcification was identified. The most commonly promulgated hypothesis is that calcification of degenerated hyalinized cells leads to the eventual formation of psammoma bodies in any organ. 9 In most situations, the concentration of calcium and phosphate in the extracellular fluid cannot initiate hydroxyapatite crystal formation, but once a crystal nidus is formed, it can sustain development of large calcified masses. The nidus within an endometrioma can originate from degenerating cells, from ruptured cell membrane material, or from calcium-rich intracellular organelles. All these possibilities are plausible. Necrosis appears to be one of the common denominators for calcification and psammoma body formation. In endometriosis, there is some necrosis of the cells as the hormonally active glandular tissue is subjected to the menstrual cycle. 10,11 Fine-needle aspiration cytologic examination of endometriomas is well documented. Aspirates of endometriomas are generally moderately cellular, containing endometrial stroma and glandular components. The ovarian tumors associated with psammoma bodies include adenofibromas, cystadenocarcinomas, and papillary adenocarcinomas. Psammoma bodies in an epithelial tumor are not diagnostic of a malignancy. 12 Psammoma bodies are seen in both benign and malignant lesions. In conclusion, although a focal calcification is pathognomonic of a dermoid, it may be occasionally seen in endometriomas. Awareness of this finding will include endometrioma in the differential diagnosis of a cystic adnexal mass containing a calcification. Also, the fluid-fluid level seen in the adnexal mass on sonography is strongly suggestive but not pathognomonic of dermoids and may be seen in endometriomas and other cystic tumors. These lesions can then be further characterized with MRI, which has the capability of differentiating blood products from fat, thus allowing a definitive diagnosis. References 1. Mais V, Guerriero S, Ajossa S, Angiolucci M, Paoletti AM, Melis GB. The efficiency of transvaginal ultrasonography in the diagnosis of endometrioma. Fertil Steril 1993; 60:776 780. 2. Patel MD, Feldstein VA, Chen DC, Lipson SD, Filly RA. Endometriomas: diagnostic performance of US. Radiology 1999; 210:739 745. 3. Fried AM, Rhodes RA, Morehouse IR. Endometrioma: analysis and sonographic classification of 51 documented cases. South Med J 1993; 86:297 301. 4. Jain KA. Prospective evaluation of adnexal masses with endovaginal gray-scale and duplex and color Doppler US: correlation with pathologic findings. Radiology 1994; 191:63 67. 5. Volpi E, De Grandis T, Zuccaro G, La Vista A, Sismondi P. Role of transvaginal sonography in the detection of endometriomas. J Clin Ultrasound 1995; 23:163 167. 1240 J Ultrasound Med 2006; 25:1237 1241

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