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Primary ovarian tumors in the pediatric patient: CT evaluation
CLINICAL IMAGING 1993;17:199-203
199
PRIMARY OVARIAN TUMORS IN THE PEDIATRIC PATIENT: CI- EVALUATION AMAL A. JABRA, MD, ELLIOT K. FISHMAN, GEORGE A. TAYLOR, MD
Primary ovarian tumors in the pediatric age group are rare with limited descriptions on computed tomography (CT). We describe the CT findings in a series of nine mature cystic teratomas, one immature teratoma, two granulosa cell tumors, and one undifferentiated small cell tumor. Four mature cystic teratomas were atypical in their CT appearance. The immature teratoma was distinguished by its large, irregular, diffusely calcified solid component. The malignant tumors were large and nearly totally solid, or if multicystic, contained a large solid component. KEY WORDS:
Pediatric: Ovary; Tumor; Computed tomography; Pathology
INTRODU(XON Primary ovarian tumors in the pediatric age group are rare. Little accurate information is available regarding the true incidence of benign and malignant tumors or their relative frequency (1). Descriptions of primary ovarian tumors on computed tomography (CT) in the pediatric age group are limited (Z-6) with no available reported pediatric series. This paper reports the CT appearance of a series of 13 pediatric ovarian tumors, including a correlation with surgical pathology findings.
From the Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins Medical Institutions, Baltimore, Maryland. Address reprint requests to: Amal A. Jabra, MD, Department of Radiology, The Johns Hopkins Hospital, 600 N. Wolfe Street, Baltimore, MD 21287. Received December 10, 1992; accepted January 5, 1993. 0 1993 Else&r Science Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0899-7u71/93/$6.00
MATERIALS
MD,
AND
AND =HODS
Pathology results, CT scans and the medical records of 11 girls with 13 primary ovarian tumors who presented between 1984 and 1992 were retrospectively reviewed. The CT findings were analyzed in terms of tumor size, laterality, density, and presence of fat or calcification. Extraovarian manifestations of ascites, adenopathy, hydronephrosis, peritoneal, mesenteric and omental implants, and solid organ metastases were also studied. The findings were correlated with information from medical records and pathologic results in all cases. The patients ranged in age from 2 to 18 years (average: 9.5 years). Scans were performed on a variety of commercially available scanners. Nine patients received oral and intravenous contrast. Two patients received oral contrast only. The CT scans were obtained in nine patients without prior diagnosis of ovarian pathology, and in two patients with prior resection of mature cystic teratoma of the ovary. In the patients without known prior ovarian pathology, the CT scans were obtained for evaluation of palpable abdominal masses or masses noted by other radiologic studies (plain films, ultrasound). Other clinical findings included abdominal pain in four patients, precocious puberty in two, constipation and enuresis in one, and renal failure in one. The two patients with prior resection of a teratoma presented with abdominal pain and adnexal mass discovered on ultrasound. RESULTS Pathology results in the nine patients without prior known ovarian pathology revealed six benign mature cystic teratomas [bilateral in one patient), one immature teratoma, two granulosa cell tumors, and one small cell undifferentiated tumor. Of the two patients with prior ovarian teratoma resection, one presented with
200
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a mature cystic teratoma of the contralateral ovary and the other presented with bilateral mature cystic teratomas. Benign
Tumors
Mature Cystic Teratomas. A specific diagnosis of mature cystic teratoma was made prospectively with CT in five out of nine lesions by identifying fat. These five lesions also showed calcifications. The distribution of fat was variable, focal peripheral in two patients (Figure lA), filling large portion of tumor in two (Figure z), and scattered within the dermoid plug in one (Figure 3). Only one patient showed a fat fluid level (Figure 3). Four mature cystic teratomas contained no fat.
A 14-year-old girl with ovarian mature cystic teratoma (arrows). Tumor is mainly cystic. Overall tumor size 11.5 x 11 x 16.5cm. (A) Note layer of fat at periphery of tumor (arrowheads). (IS)Higher level shows focal calcification adjacent to uppermost aspect of fat layer (arrowhead).
FIGURE 1.
FIGURE 2. A g-year-old girl with ovarian mature cystic teratoma (large arrows). Overall size 13 x 12 x 10 cm. Note pe-
ripheral calcifications (small arrows). At other levels, these were more numerous and covering a major part of the tumor border. Also note daughter cyst anteriorly and focal collections of fat (circular and triangular low density areas) posteriorly and peripherally. Three were cystic and one was near totally cystic with few peripheral septae and calcification (Figure 4). Two were filled with serous fluid and two with sebum pathologically. Focal solid components arising from tumor wall (Rokitansky protuberance or dermoid plug) were seen
A l&year-old girl with mature cystic teratoma of left ovary (large arrows). Note large Rokitansky protuberance [arrowheads) containing areas of fat, calcium, and solid and cystic components. The protuberance was largely multicystic. Note fat-fluid level (small arrow).
FIGURE 3.
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1993
CT OF PEDIATRIC PRIMARY OVARIAN
TUMORS
201
Calcification was noted in six of nine tumors. Tumors were bilateral in two patients. Tumor size ranged from 1.5 to 29 cm in maximal diameter (average 9 cm). None of the patients showed ascites or hydronephrosis. Pathology results were in agreement with the CT findings in terms of presence of Rokitansky protuberance and calcification with the exception of one 2.5 cm cystic lesion in which a small (< 1 cm) calcified protuberance was only noted pathologically This lesion measured 16 x 20 a large (9 cm diameter) Rokitansky protuberance. The protuberance was solid with diffuse scattered calcifications, had irregular frondlike borders and few small areas of fat (Figure 5). Immature
TerQtOIIIQ.
x 10 cm. It was largely cystic but contained
FIGURE 4. A u-year-old girl with left ovarian mature cystic teratoma [arrows). Tumor is predominantly cystic, nonfatcontaining with small peripheral solid component seen as septae and focal calcification (arrowhead). in six mature cystic teratomas and were of variable appearance. This was seen as calcification surrounded calcification surrounded by fat (3 lesions, Figure lB), by septae (1lesion, Figure 4)) and as a multilobulated area containing daughter cysts, soft tissue components, fat and calcification in one lesion (Figure 3). One tumor contained numerous peripheral chunky calcifications with multiple daughter cysts and fat collections throughout the lesion (Figure 2). The largest protuberance measured 17 x 15 x 12 cm and was largely multicystic (Figure 3). The other protuberances ranged from 2 to 4 cm in size.
FIGURE 5. A Q-year-old girl with ovarian immature tera-
toma (large arrows). The 16 x 20 x 10 cm tumor is predominantly cystic but contains a large solid Rokitansky protuberance (9cm in maximal diameter). Periphery of protuberance is irregular. Note diffuse coarse calcifications, and areas of fat (small arrows).
Malignant
Tumors
GrQnulosQ Cell Tumors. Granulosa cell tumor appeared as a solid 9 x 6 x 9 cm mass with occasional small hypodense areas in a 29month-old girl. It contained no fat or calcification and was associated with mild unilateral hydronephrosis. The mass was described as firm, lobulated, and homogeneous on pathology. In the second girl (6 years old), the tumor appeared as a multicystic mass measuring 11 x 11 x 7 cm with coarse septae and focal solid soft tissue components without fat or calcification (Figure 6). Though containing a large solid component, the major portion of this tumor was multicystic. On pathology it was described as partly cystic and partly solid with some areas showing marked atypia, hyperchromaticity, and mitoses. No ascites or metastasis was present in either of the two patients. Undifferentiated Small Cell Tumor. An l&year-old girl presented with a 20 x 18 x 14 cm mass that appeared predominantly solid with a few large irregular low density areas characteristic of hemorrhage or necrosis (Figure 7). No fat or calcification was present on CT or pathologically. At presentation, CT showed metastasis to lungs, liver (central and peripheral), periaortic adenopathy, and bilateral hydronephrosis with poor renal contrast excretion bilaterally. No peritoneal wall or omental implants or ascites were seen.
DISCUSSION Pediatric primary ovarian tumors are rare. Tumors of germ cell origin account for the majority of cases (58% to 80%). Tumors of epithelial origin are reported to be slightly higher in frequency than those of stromal
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JABRA ET AL.
CLINICAL IMAGING VOL. 17, NO. 3
and distal metastases. In this paper, we report the CT findings in 11 patients with nine mature cystic teratomas, one immature teratoma, two granulosa cell tumors, and one undifferentiated small cell tumor. Benign
A6-year-oldgirlwithan 11 x 11 x 7cmovarian granulosa cell tumor (white arrows). Tumor is predominantly
FIGURE6.
cystic with solid areas [black arrows) seen mainly at the periphery. More solid components seen at other levels.
origin in some series and 2 to 5 times higher in frequency in other series (1). In the germ cell tumor category, the percentage of malignant tumors decreases with age while the mature cystic teratoma-the most common ovarian childhood tumor-increases with age. Sonography is usually the initial diagnostic study of choice in the evaluation of pelvic masses in the pediatric patient (2). Computed tomography is useful when further evaluation is needed concerning site of origin, nature of mass (presence of fat or calcification) extent
FIGURE 7. An ll-year-old girl with undifferentiated small cell tumor (arrows). Tumor is predominantly solid, somewhat lobulated with la&e hypodense areas reprksenting necrosis or hemorrhage. Overall size is 20 x 18 x 14 cm.
Tumors
Mature Cystic Teratomas. Although fat can be occasionally seen in a few ovarian tumors, its presence is nearly always indicative of a teratoma. In our series, five of nine mature cystic teratomas and the immature teratoma showed fat on CT. Fewer mature cystic teratomas showed fat in our series than reported in the literature (55% in our series versus 93% in a larger predominantly adult series by Buy et al. [7)). This resulted in less definite diagnosis by CT. The difference is of uncertain significance since our tumor number is smaller (9 versus 43). Larger series in children are needed for a more valid comparison. The distribution and amount of fat was variable. Sixty-seven percent of mature cystic teratomas in our series showed a Rokitansky protuberance on CT in comparison with 81% in the Buy et al. series. Calcification was seen in 67% in comparison with 56% in the Buy et al. series. Nonfat-containing mature cystic teratomas caused some difficulty in diagnosis. In one large cystic lesion, peripheral focal calcifications were missed initially and diagnostic possibilities were centered on cysts (such as mesenteric or duplication). In one patient, bilateral small teratomas were seen as ovarian cysts. History of prior teratoma resection and increasing levels of serum alpha fetoprotein raised suspicion of the correct diagnosis though appearance was nondiagnostic. In another patient, a small cystic teratoma was thought
to represent
part of a much larger contralateral
cystic tumor. Immature Teratoma. Although immature teratoma is not malignant, it should be differentiated from mature cystic teratoma for prognostic and management considerations. Immature teratomas higher than Grade I show a propensity to recur and should receive additional chemotherapy (8). The immature cystic teratoma was not suspected as such on CT. Retrospective analysis of its appearance on CT showed that the tumor was distinctly different from all the other mature cystic teratomas (Figure 5). Its dermoid plug or Rokitansky protuberance was solid with diffuse scattered calcifications without focal cystic areas. Its borders on the surrounding cystic area were irregular and frondlike. Its size was the second largest Rokitansky protuberance in our series. Buy et al. (7), in a review of 43 mature cystic teratomas, suggested that a large (> 5 cm) solid Rokitansky protuberance and irregularity of the pro-
JULY-SEPTEMBER
tuberance are two characteristics that suggest malignant transformation of a mature cystic teratoma. We suggest that these characteristics should also raise the possibility of immature tertoma. Immature teratomas are described as characteristically predominantly solid with scattered calcification, but could occasionally be comprised almost entirely of cysts (9).
Malignant
CT OF PEDIATRIC PRIMARY OVARIAN TUMORS
1993
Tumors
These were large (9 to 20 cm in maximal diameter), predominantly solid, or containing a large solid component if multicystic. This is in agreement with prior reports (2, 9). Granulosa Cell Tumors. Granulosa Cell Tumors are stromal neoplasms of generally low-grade malignancy. They are rare before puberty, but when they occur are associated with precocious pseudopuberty (10). Both of our patients had precocious pseudopuberty which brought them to medical attention. The CT appearance was variable, being nearly totally solid in one tumor. The second tumor was more complex and predominantly multicystic with a relatively large solid component (Figure 6). Neither contained fat or calcification. Undifferentiated Small Cell Tumor. Poorly differentiated tumors of the ovary are rare and cause difficulties in microscopic diagnosis. Our tumor showed possible areas of epithelial differentiation, but the consensus of the pathologists was that of an undifferentiated small cell tumor. On CT, the tumor appeared complex, predominantly solid with large low-density areas without fat, calcification, or ascites (Figure 7). It presented with distant metastasis and was the second largest in our series (one mature cystic teratoma was larger).
203
CONCLUSION The diagnosis of mature cystic teratoma is usually easy on CT in the presence of fat that may also be associated with calcification in a cystic-appearing tumor. A relatively larger number of mature cystic teratomas in our series were atypical when compared with adult series. Our numbers, however, are smaller and this is of uncertain significance. Although the appearance of the Rokitansky protuberance is variable, its large size, diffuse calcification, and more importantly, solid nature may suggest immature teratoma. The malignant tumors were large and contained more solid components than benign lesions, which is in agreement with prior reports. REFERENCES 1.
Norris HJ, Jensen RD. Relative frequency of ovarian neoplasms in children and adolescents. Cancer 1972;30:713-719.
2.
Surratt JT, Siegel MJ. Imaging of pediatric RadioGraphics 1991;11:533-548.
ovarian masses.
3. Friedman AC, Pyatt RS, Hartman DS, Downey EF, Olson WB. CT of benign cystic teratomas. AJR 1982;138:659-665. 4. Gross BH, Moss AA, Mihara K, Goldberg HI, Glazer GM. Computed tomography of gynecologic diseases. AJR 1983; 14:765-773. 5. Sty JR, Wells RG. Other abdominal and pelvic masses in children. Semin Roentgen01 1988;23:216-231. 6. Kawamura N, Kamoi I, Shigyo R. Sclerosing of the ovary. Br J Radio1 1987;60:1031-1033. z
stromal tumour
Buy J-N, Ghossain MA, Moss AA, Bazot M, Doucet M, Hugo1 D, Turc JB, Poitout P, Ecoiffier J. Cystic teratoma of the ovary: CT detection. Radiology 1989;171:697-701.
8. Gershenson DM, Del Junco G, Silva EG, Copeland LJ, Wharton JT, Rutledge FN. Immature teratoma of the ovary. Obstet Gynecol 1986;68:624-629. 9. Brammer HM, Buck JL, Hayes WS, Sheth S, Tavassoli FA. Malignant germ cell tumors of the ovary: radiologic-pathologic correlation. RadioGraphics 1990;10:715-724. 10. Copeland LJ. Malignant gynecologic tumors. In Sutow WW, Fernbach DJ, Vietti TJ, eds: Clinical Pediatric Oncology St. Louis: CV Mosby, 1984;744-760.
199
PRIMARY OVARIAN TUMORS IN THE PEDIATRIC PATIENT: CI- EVALUATION AMAL A. JABRA, MD, ELLIOT K. FISHMAN, GEORGE A. TAYLOR, MD
Primary ovarian tumors in the pediatric age group are rare with limited descriptions on computed tomography (CT). We describe the CT findings in a series of nine mature cystic teratomas, one immature teratoma, two granulosa cell tumors, and one undifferentiated small cell tumor. Four mature cystic teratomas were atypical in their CT appearance. The immature teratoma was distinguished by its large, irregular, diffusely calcified solid component. The malignant tumors were large and nearly totally solid, or if multicystic, contained a large solid component. KEY WORDS:
Pediatric: Ovary; Tumor; Computed tomography; Pathology
INTRODU(XON Primary ovarian tumors in the pediatric age group are rare. Little accurate information is available regarding the true incidence of benign and malignant tumors or their relative frequency (1). Descriptions of primary ovarian tumors on computed tomography (CT) in the pediatric age group are limited (Z-6) with no available reported pediatric series. This paper reports the CT appearance of a series of 13 pediatric ovarian tumors, including a correlation with surgical pathology findings.
From the Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins Medical Institutions, Baltimore, Maryland. Address reprint requests to: Amal A. Jabra, MD, Department of Radiology, The Johns Hopkins Hospital, 600 N. Wolfe Street, Baltimore, MD 21287. Received December 10, 1992; accepted January 5, 1993. 0 1993 Else&r Science Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0899-7u71/93/$6.00
MATERIALS
MD,
AND
AND =HODS
Pathology results, CT scans and the medical records of 11 girls with 13 primary ovarian tumors who presented between 1984 and 1992 were retrospectively reviewed. The CT findings were analyzed in terms of tumor size, laterality, density, and presence of fat or calcification. Extraovarian manifestations of ascites, adenopathy, hydronephrosis, peritoneal, mesenteric and omental implants, and solid organ metastases were also studied. The findings were correlated with information from medical records and pathologic results in all cases. The patients ranged in age from 2 to 18 years (average: 9.5 years). Scans were performed on a variety of commercially available scanners. Nine patients received oral and intravenous contrast. Two patients received oral contrast only. The CT scans were obtained in nine patients without prior diagnosis of ovarian pathology, and in two patients with prior resection of mature cystic teratoma of the ovary. In the patients without known prior ovarian pathology, the CT scans were obtained for evaluation of palpable abdominal masses or masses noted by other radiologic studies (plain films, ultrasound). Other clinical findings included abdominal pain in four patients, precocious puberty in two, constipation and enuresis in one, and renal failure in one. The two patients with prior resection of a teratoma presented with abdominal pain and adnexal mass discovered on ultrasound. RESULTS Pathology results in the nine patients without prior known ovarian pathology revealed six benign mature cystic teratomas [bilateral in one patient), one immature teratoma, two granulosa cell tumors, and one small cell undifferentiated tumor. Of the two patients with prior ovarian teratoma resection, one presented with
200
JABRAETAL.
CLINICAL IMAGING VOL. 17,NO. 3
a mature cystic teratoma of the contralateral ovary and the other presented with bilateral mature cystic teratomas. Benign
Tumors
Mature Cystic Teratomas. A specific diagnosis of mature cystic teratoma was made prospectively with CT in five out of nine lesions by identifying fat. These five lesions also showed calcifications. The distribution of fat was variable, focal peripheral in two patients (Figure lA), filling large portion of tumor in two (Figure z), and scattered within the dermoid plug in one (Figure 3). Only one patient showed a fat fluid level (Figure 3). Four mature cystic teratomas contained no fat.
A 14-year-old girl with ovarian mature cystic teratoma (arrows). Tumor is mainly cystic. Overall tumor size 11.5 x 11 x 16.5cm. (A) Note layer of fat at periphery of tumor (arrowheads). (IS)Higher level shows focal calcification adjacent to uppermost aspect of fat layer (arrowhead).
FIGURE 1.
FIGURE 2. A g-year-old girl with ovarian mature cystic teratoma (large arrows). Overall size 13 x 12 x 10 cm. Note pe-
ripheral calcifications (small arrows). At other levels, these were more numerous and covering a major part of the tumor border. Also note daughter cyst anteriorly and focal collections of fat (circular and triangular low density areas) posteriorly and peripherally. Three were cystic and one was near totally cystic with few peripheral septae and calcification (Figure 4). Two were filled with serous fluid and two with sebum pathologically. Focal solid components arising from tumor wall (Rokitansky protuberance or dermoid plug) were seen
A l&year-old girl with mature cystic teratoma of left ovary (large arrows). Note large Rokitansky protuberance [arrowheads) containing areas of fat, calcium, and solid and cystic components. The protuberance was largely multicystic. Note fat-fluid level (small arrow).
FIGURE 3.
JULY-SEPTEMBER
1993
CT OF PEDIATRIC PRIMARY OVARIAN
TUMORS
201
Calcification was noted in six of nine tumors. Tumors were bilateral in two patients. Tumor size ranged from 1.5 to 29 cm in maximal diameter (average 9 cm). None of the patients showed ascites or hydronephrosis. Pathology results were in agreement with the CT findings in terms of presence of Rokitansky protuberance and calcification with the exception of one 2.5 cm cystic lesion in which a small (< 1 cm) calcified protuberance was only noted pathologically This lesion measured 16 x 20 a large (9 cm diameter) Rokitansky protuberance. The protuberance was solid with diffuse scattered calcifications, had irregular frondlike borders and few small areas of fat (Figure 5). Immature
TerQtOIIIQ.
x 10 cm. It was largely cystic but contained
FIGURE 4. A u-year-old girl with left ovarian mature cystic teratoma [arrows). Tumor is predominantly cystic, nonfatcontaining with small peripheral solid component seen as septae and focal calcification (arrowhead). in six mature cystic teratomas and were of variable appearance. This was seen as calcification surrounded calcification surrounded by fat (3 lesions, Figure lB), by septae (1lesion, Figure 4)) and as a multilobulated area containing daughter cysts, soft tissue components, fat and calcification in one lesion (Figure 3). One tumor contained numerous peripheral chunky calcifications with multiple daughter cysts and fat collections throughout the lesion (Figure 2). The largest protuberance measured 17 x 15 x 12 cm and was largely multicystic (Figure 3). The other protuberances ranged from 2 to 4 cm in size.
FIGURE 5. A Q-year-old girl with ovarian immature tera-
toma (large arrows). The 16 x 20 x 10 cm tumor is predominantly cystic but contains a large solid Rokitansky protuberance (9cm in maximal diameter). Periphery of protuberance is irregular. Note diffuse coarse calcifications, and areas of fat (small arrows).
Malignant
Tumors
GrQnulosQ Cell Tumors. Granulosa cell tumor appeared as a solid 9 x 6 x 9 cm mass with occasional small hypodense areas in a 29month-old girl. It contained no fat or calcification and was associated with mild unilateral hydronephrosis. The mass was described as firm, lobulated, and homogeneous on pathology. In the second girl (6 years old), the tumor appeared as a multicystic mass measuring 11 x 11 x 7 cm with coarse septae and focal solid soft tissue components without fat or calcification (Figure 6). Though containing a large solid component, the major portion of this tumor was multicystic. On pathology it was described as partly cystic and partly solid with some areas showing marked atypia, hyperchromaticity, and mitoses. No ascites or metastasis was present in either of the two patients. Undifferentiated Small Cell Tumor. An l&year-old girl presented with a 20 x 18 x 14 cm mass that appeared predominantly solid with a few large irregular low density areas characteristic of hemorrhage or necrosis (Figure 7). No fat or calcification was present on CT or pathologically. At presentation, CT showed metastasis to lungs, liver (central and peripheral), periaortic adenopathy, and bilateral hydronephrosis with poor renal contrast excretion bilaterally. No peritoneal wall or omental implants or ascites were seen.
DISCUSSION Pediatric primary ovarian tumors are rare. Tumors of germ cell origin account for the majority of cases (58% to 80%). Tumors of epithelial origin are reported to be slightly higher in frequency than those of stromal
202
JABRA ET AL.
CLINICAL IMAGING VOL. 17, NO. 3
and distal metastases. In this paper, we report the CT findings in 11 patients with nine mature cystic teratomas, one immature teratoma, two granulosa cell tumors, and one undifferentiated small cell tumor. Benign
A6-year-oldgirlwithan 11 x 11 x 7cmovarian granulosa cell tumor (white arrows). Tumor is predominantly
FIGURE6.
cystic with solid areas [black arrows) seen mainly at the periphery. More solid components seen at other levels.
origin in some series and 2 to 5 times higher in frequency in other series (1). In the germ cell tumor category, the percentage of malignant tumors decreases with age while the mature cystic teratoma-the most common ovarian childhood tumor-increases with age. Sonography is usually the initial diagnostic study of choice in the evaluation of pelvic masses in the pediatric patient (2). Computed tomography is useful when further evaluation is needed concerning site of origin, nature of mass (presence of fat or calcification) extent
FIGURE 7. An ll-year-old girl with undifferentiated small cell tumor (arrows). Tumor is predominantly solid, somewhat lobulated with la&e hypodense areas reprksenting necrosis or hemorrhage. Overall size is 20 x 18 x 14 cm.
Tumors
Mature Cystic Teratomas. Although fat can be occasionally seen in a few ovarian tumors, its presence is nearly always indicative of a teratoma. In our series, five of nine mature cystic teratomas and the immature teratoma showed fat on CT. Fewer mature cystic teratomas showed fat in our series than reported in the literature (55% in our series versus 93% in a larger predominantly adult series by Buy et al. [7)). This resulted in less definite diagnosis by CT. The difference is of uncertain significance since our tumor number is smaller (9 versus 43). Larger series in children are needed for a more valid comparison. The distribution and amount of fat was variable. Sixty-seven percent of mature cystic teratomas in our series showed a Rokitansky protuberance on CT in comparison with 81% in the Buy et al. series. Calcification was seen in 67% in comparison with 56% in the Buy et al. series. Nonfat-containing mature cystic teratomas caused some difficulty in diagnosis. In one large cystic lesion, peripheral focal calcifications were missed initially and diagnostic possibilities were centered on cysts (such as mesenteric or duplication). In one patient, bilateral small teratomas were seen as ovarian cysts. History of prior teratoma resection and increasing levels of serum alpha fetoprotein raised suspicion of the correct diagnosis though appearance was nondiagnostic. In another patient, a small cystic teratoma was thought
to represent
part of a much larger contralateral
cystic tumor. Immature Teratoma. Although immature teratoma is not malignant, it should be differentiated from mature cystic teratoma for prognostic and management considerations. Immature teratomas higher than Grade I show a propensity to recur and should receive additional chemotherapy (8). The immature cystic teratoma was not suspected as such on CT. Retrospective analysis of its appearance on CT showed that the tumor was distinctly different from all the other mature cystic teratomas (Figure 5). Its dermoid plug or Rokitansky protuberance was solid with diffuse scattered calcifications without focal cystic areas. Its borders on the surrounding cystic area were irregular and frondlike. Its size was the second largest Rokitansky protuberance in our series. Buy et al. (7), in a review of 43 mature cystic teratomas, suggested that a large (> 5 cm) solid Rokitansky protuberance and irregularity of the pro-
JULY-SEPTEMBER
tuberance are two characteristics that suggest malignant transformation of a mature cystic teratoma. We suggest that these characteristics should also raise the possibility of immature tertoma. Immature teratomas are described as characteristically predominantly solid with scattered calcification, but could occasionally be comprised almost entirely of cysts (9).
Malignant
CT OF PEDIATRIC PRIMARY OVARIAN TUMORS
1993
Tumors
These were large (9 to 20 cm in maximal diameter), predominantly solid, or containing a large solid component if multicystic. This is in agreement with prior reports (2, 9). Granulosa Cell Tumors. Granulosa Cell Tumors are stromal neoplasms of generally low-grade malignancy. They are rare before puberty, but when they occur are associated with precocious pseudopuberty (10). Both of our patients had precocious pseudopuberty which brought them to medical attention. The CT appearance was variable, being nearly totally solid in one tumor. The second tumor was more complex and predominantly multicystic with a relatively large solid component (Figure 6). Neither contained fat or calcification. Undifferentiated Small Cell Tumor. Poorly differentiated tumors of the ovary are rare and cause difficulties in microscopic diagnosis. Our tumor showed possible areas of epithelial differentiation, but the consensus of the pathologists was that of an undifferentiated small cell tumor. On CT, the tumor appeared complex, predominantly solid with large low-density areas without fat, calcification, or ascites (Figure 7). It presented with distant metastasis and was the second largest in our series (one mature cystic teratoma was larger).
203
CONCLUSION The diagnosis of mature cystic teratoma is usually easy on CT in the presence of fat that may also be associated with calcification in a cystic-appearing tumor. A relatively larger number of mature cystic teratomas in our series were atypical when compared with adult series. Our numbers, however, are smaller and this is of uncertain significance. Although the appearance of the Rokitansky protuberance is variable, its large size, diffuse calcification, and more importantly, solid nature may suggest immature teratoma. The malignant tumors were large and contained more solid components than benign lesions, which is in agreement with prior reports. REFERENCES 1.
Norris HJ, Jensen RD. Relative frequency of ovarian neoplasms in children and adolescents. Cancer 1972;30:713-719.
2.
Surratt JT, Siegel MJ. Imaging of pediatric RadioGraphics 1991;11:533-548.
ovarian masses.
3. Friedman AC, Pyatt RS, Hartman DS, Downey EF, Olson WB. CT of benign cystic teratomas. AJR 1982;138:659-665. 4. Gross BH, Moss AA, Mihara K, Goldberg HI, Glazer GM. Computed tomography of gynecologic diseases. AJR 1983; 14:765-773. 5. Sty JR, Wells RG. Other abdominal and pelvic masses in children. Semin Roentgen01 1988;23:216-231. 6. Kawamura N, Kamoi I, Shigyo R. Sclerosing of the ovary. Br J Radio1 1987;60:1031-1033. z
stromal tumour
Buy J-N, Ghossain MA, Moss AA, Bazot M, Doucet M, Hugo1 D, Turc JB, Poitout P, Ecoiffier J. Cystic teratoma of the ovary: CT detection. Radiology 1989;171:697-701.
8. Gershenson DM, Del Junco G, Silva EG, Copeland LJ, Wharton JT, Rutledge FN. Immature teratoma of the ovary. Obstet Gynecol 1986;68:624-629. 9. Brammer HM, Buck JL, Hayes WS, Sheth S, Tavassoli FA. Malignant germ cell tumors of the ovary: radiologic-pathologic correlation. RadioGraphics 1990;10:715-724. 10. Copeland LJ. Malignant gynecologic tumors. In Sutow WW, Fernbach DJ, Vietti TJ, eds: Clinical Pediatric Oncology St. Louis: CV Mosby, 1984;744-760.