Journ al of the Korean Radiological Society 1996: 35(6) ’ 949 - 955 CT Findings of Ovarian Teratomas: Mature versus Immature' Jong Chul Kim, M.D., Young Wol Kim, M.D. Purpose : To differentiate mature and immature ovarian teratomas, using CT findings. Materials and Methods : The CT findings of ten mature ovarian teratomas (in one patient, bilateral) and ten which were immature were compared, using stat­ istical analysis. Images were evaluated for size, margins, architecture, contents (mural nodules, fat, calcification), septa, local invasion and distant metastasis. These findings were compared with pathologic findings. Results : Of the ten mature tumors, nine were well defined and predominantly cystic in internal architecture, and one was mixed. Mural nodules were found in six tumors, fat in all, distinct calcification in seven, and regular septa in three lesions. Of the ten immature tumors, eight had irregular margins. Seven were predominantly solid in internal architecture and irregularly enhanced, two were mixed, and one was mainly cystic. Fat was detected in five lesions, indistinct scat­ tered calcification in six, irregular septa in three, and local invasion or distant metastasis i n four patients. Conclusion : Compared with mature ovarian teratomas, those that are imma­ ture tend to show CT findings of marginal irregularity, solid mass with irregular enhancement, scattered indistinct calcifications, septal irregularity, local in­ vasion or distant metastasis. Our experience suggests that these findings may be helpful in differentiation of mature and immature ovarian teratomas. Index Words : Ovary, neoplasms Ovary, CT Teratoma In patients aged less than 21 , the majority of ovarian surgical resection (4). Immature teratomas are treated tumors are of germ celi origin, and of these more than surgicaliy and with multiagent chemotherapy. It is im­ 40 % are malignant. Of many kinds of germ celi tumors, portant to distinguish a benign mature teratoma from only mature teratomas, which are almost always cystic, one that is immature, since due to the frequent invasion are benign (1). Teratomas are benign or malignant of surrounding structures the latter cannot be com­ neoplasms that are derived from primordial germ celis pletely excised (5). and can arise in the gonads or in extragonadal Ultrasonography is useful in detecting ovarian locations. They are most common in the sacroco­ teratomas, but typical sonographic features are found ccygeal region , while the ovary is the next most fre­ in less than 50 % of lesions (6, 7l. CTfindings character­ quent primary site (2, 3) istic of teratomas (i.e. fat or fat and calcification) have Mature cystic teratomas make up approximately 25 been reported in 65 % of lesions (8, 9). There have, % of all ovarian neoplasms, and are usualiy treated by however, been only a few reports which differentiate mature and immature teratomas on CT findings (1 이 The purpose of this study is to differentiate mature 'Department 01 Diagnostic Radiology , Chungnam National University School 01 Medici ne and immature ovarian teratomas, using CT findings. Received July23. 1996: Accepted September 24 , 1996 Address reprint requests to: Jong Chul Kim , M. 0. , Department 01 Diagnostic MATERIALSand METHODS Radiology , Chungnam National Un iversity School 이 M edi c ine ， ; 640 Daesa.dong , Jung-ku , Taejeon , 301-040 , Korea TeI82.42.220.7835 , Fax 82-42-253-0061 The CT findings of nine patients with mature ovarian -949 - Journ al of th e Korean Radiologi cal Society 1996 : 35 (6) : 949-955 teratomas (in one case, bilateral) and ten with those components) , and mixed (10-50 % softtissuecompon­ which were immature were retrospectively reviewed ents). Local invasion on CT was based on the presence and com pared. Between 1984 and 1996, all 20 teratom­ of tumor infiltration into the fat planes around the mass as were surgically resected and pathologically proven. or encasement of vessels. Findings related to the abov­ The age of the patients ranged from two months to 32 e radiologic criteria were analyzed by two radiologists, years (mean, 16 years). In addition to CT findings, tum­ who reached a consensus. or markers [serum α-fetoprotein (FP) and human chori­ CT and pathologic findings were compared. The onic gonadotropin (HCG)] in each patient were also re­ chi-square test and Fisher’s exact test were used to viewed. evaluate the significance of CT findings in the differen­ CT was performed with a GE 8800 or GE Advantage tial diagnosis of mature and immature ovarian teratom­ High Speed (General Electric Medical Systems, Mil­ as. waukee, Wisconsin , USA) ; continuous precontrast and postcontrast scans from the symphysis pubis to the il­ RESULTS iac crest were obtained at 8 or 1 Omm intervals, with 5 mm slice thickness, during shallow breathing or sus­ Mature teratomas were found in patients aged be­ pended expiration. tween 15 to 32 years (mean , 22) , while immature ter­ Images were evaluated for the CD size, (g) margins atomas were found in those aged between two months (smooth , well defined versus irregular, ill defined), @ and 14 years (mean, 10 years). Thus patients with ma­ internal architecture (cystic, sOlid , or mixed, according ture ovarian teratomas were older than those with im­ to the percentage of low attenuation or soft tissue com­ mature tumors (P=0.0002). Five of ten immature ter­ ponents) , @ contents (mural nod 비 es ， fat, the shape atomas (50 %) had elevated α- FP levels, but, all mature and location of calcifications) , @ septa in multilocular teratomas had normallevels oftumor markers mass (regular, even, thin septum of less than 3mm in The comparative CT findings of mature and imma­ thickness versus irregular, uneven , thick septum of ture ovarian teratomas are summarized in Table 1. more than 3mm in thickness) , @ local invasion, and (j) Their largest diameters ranged from 3. 5 to 20 cm; even distant metastasis. Low attenuation cystic components though the mean diameter of immature teratomas was were defined as areas having CT attenuation values greater than that of mature teratomas, there was no ranging from 10 to 20 Hounsfield units, whereas softtis­ statistically significant difference in size between ma­ sue components had densities equal to muscle densit­ ture and immature lesions. Tumor margins were smoot­ ies. Based on internal consistency, tumors were classi­ h and well defined in eleven lesions (Fig. 1, 2, 3) , and ir­ fied as cystic (Iess than 10 % soft tissue components of regular and ill defined in nine (Fig. 4) . Nine tumors (81 .8 whole tumor volume) , solid (more than 50 % soft tissue %) with smooth margins were mature and two (18.2 a b Fig. 1 . Contrast enhanced CT scan s of bilateral multilocular mature teratomas. a. CT scan through th e mid-pelvis shows a large multilocular cystic mass with smooth well defined margin. It contai ns multiple distinct and di screte calcifi cations in mural nodul es and hypodense fatty areas (white arrows). The septa are thin and regular (black arrow­ head s) b. CT scan at a lower level demonstrates a multiseptated cystic mass with fat and cal cifications in mural nodules (black arrowhead) Th ere is anoth er sm all cystic mass with somewhat irregular margin and mural nodules (white ar rows) in the right side of the uterus (UT). Th e resected specimens showed a large mature multilocular cystic teratoma in the left ovary and a small dermoid cyst in the right 。v ary ， which contained primaril y serous f1 uid , sebum and small mural nodules with fat and calcifications. 950 Jong Chul Kim, et al ’ CT Findings of Ovarian Teratomas .... ‘ ’ Fig. 2 . Contrast enhanced CT scan of a mature cystic teratoma. Fig. 3. Contrast enhanced CT scan of a benign mature teratoma CT scan through the upper pelvis demonstrates a well defined CT scan through the mid-pelvis demonstrates a well defined, cystic mass with m 비 tiple mural nodules in the posterior wall multilocular cystic mass with calcification in a mural nodule in (arrows) in the right side of the pelvis. The CT number of the in- the posterior wall , mulberry shaped solid portions attached to the ner homogeneous hypodense content was -40 H.U. Pathologic left lateral wall (white arrow), and hypodense fatty content in the specimen revealed a dermoid cyst containing sebaceous fluid left side of the pelvic cavity. The inner septa are linear, thin , and and hairs in the right ovary. regular in thickness (black arrowheads). Pathologic examination revealed a left ovarian mature teratoma composed of sebum, calci fication and hair a b Fig. 4 . Contrast enhanced CT scans of a large multilocular immature teratoma a. CT scan through the mid-pelvis shows a large multilocular cystic and solid mass with somewhat irregular posterior margin, occupy­ ing the entire pelvis. It contains multiple irregularly enhanced solid portions, some scattered small calcific foci (arrowheads), and sev- eral tiny hypodense fatty areas. The septa are thick and irregular b. CT scan at a lower level demonstrates a multiseptated cystic and sol id mass with hypodense fat, and i rregularly enhanced soft tissue scattered through the posterior two third portions of the mass. The margins of this mass were irregular except the anterior cystic portion. The resected specimen showed a large immature teratoma of multilocular mi xed nature in the right ovary with immature elements, tiny cyst, fat and calcifications. Pathology revealed extraovarian local soft tissue invasion of this grade 1 immature tera­ toma %) were immature. Eighttumors (88.9 %) with irregular 90 % soft tissue content (Fig. 5 , 6a). A complex mixed margins were immature and one was mature (P=O. mass with 10-50 % soft tissue content was seen in three 00548) of 20 cases (15 %) ; the soft tissue content was 40 % in A cystic mass with predominantly f luid and less than one mature lesion (Fig. 3) , and 45-50 % in two immature 10 % soft tissue content was seen in ten of 20 cases (50 lesions (Fig.