Mapping
Intravascular Magnetic
Extension Resonance
By Donald L. Weese, Harry Applebaum, Los Angeles, l Accurate preoperative diagnosis of renal vein, vena caval, or intracardiac extension of Wilms’ tumor allows the surgeon to better plan operative vascular control and assess the potential benefits of preoperative chemotherapy. Magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound were used to study four consecutive patients presenting with Wilms’ tumor. Three had vena caval involvement, with one of these having a massive right atrial tumor thrombus. A fourth patient had renal vein involvement only. We found MRI to be superior to both CT and ultrasound for mapping intravascular extension of Wilms’ tumor and for delineating nonvascular disease. Because of its noninvasiveness, multiplane imaging capabilities, and image contrast and resolution, MRI is a valuable complimentary imaging modality for the diagnosis and follow-up of patients with Wilms’ tumor. Copyright o 1991 by W.B. Saunders Company INDEX WORDS: Wilms’ tumor, intravascular; nance imaging.
magnetic reso-
V
ASCULAR EXTENSION of Wilms’ tumor is a well known phenomenon. Renal vein involvement occurs in 15% to 20% of patients. Vena caval extension occurs in 5% to lo%, and intracardiac extension is reported in 0.5% to 1% of cases.‘-’ Intravascular involvement with Wilms’ tumor represents a significant challenge for the surgeon. The ability to remove a tumor thrombus intact without embolization can have direct bearing on patient management and prognosis; therefore, accurate preoperative diagnosis of vascular extension and careful planning of operative vascular control is essentia1.3r6.’ Traditional surgical management of caval involvement often required major vascular surgery, and cardiac tumor was optimally managed via atriotomy in conjunction with cardiopulmonary bypass3** Accurate information regarding tumor extension affords the surgeon the opportunity to consider the potential benefits of preoperative chemotherapy, which can sometimes eliminate the need for major vascular surgery. From the Depatiments of Surgery and Radiology, Kaiser Permanente Medical Center, Los Angeles, CA. Date accepted: February 20, 1990. Address reprint requests to Harry Applebaum, MD, Kaiser Permanente Medical Center, 1526 N Edgemont St, Los Angeles, CA 90027. Copyright o 1991 by WB. Saunders Company 0022-3468/9112601-OOI5$03.OOiO
64
of Wilms’ Tumor With Imaging and Paddy Taber
California
A variety of imaging studies have been used for the diagnosis and follow-up of intravascular Wilms’ tumor. A consensus opinion regarding which is the optimal study has not been reached. This paper compares the ability of magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound to assess vascular tumor extension in four consecutive patients presenting with Wilms’ tumor. CASE REPORTS Case 1 This 3-year-old girl presented to another facility on March 7, 1988, with abdominal pain and distension. Physical examination showed a pulse of 110 beatsimin, respiration 20 breathsimin, temperature 37.5”C, and blood pressure 100/76 mm Hg. A II/VI systolic ejection murmur and a large, smooth left abdominal mass were present. A CT scan of the abdomen was interpreted as showing a large left renal mass without vascular extension or suggestion of bilateral disease. However, retrospective analysis of the CT scan does suggest vascular extension and bilateral@. Ultrasound showed a left renal mass with renal vein involvement and inferiorvena cava (IVC) involvement. After the ultrasound the patient became tachycardiac and tachypneic and was transferred to this hospital for further evaluation. A two-dimensional echocardiogram was then obtained, which showed a massive right atrial tumor thrombus. An MRI confirmed the presence of a large left renal mass extending to the midline and a massive tumor thrombus that extended into the heart and occupied 90% of the right atrium. The MRI also showed complete subdiaphragmatic vena caval occlusion with dilated azygos and hemiazygos venous systems (Fig 1). A small lower pole right renal lesion was also visualized on MRI scan. Under ultrasonic guidance a needle biopsy of the renal mass was performed, which demonstrated Wilms’ tumor of favorable histological type. Chemotherapy with vincristine and actinomycin D was begun. During the first course of chemotherapy the patient’s tachycardia and tachypnea resolved. After the first course of chemotherapy echocardiography showed a significant decrease in the size of the atrial thrombus. Over 15 weeks she received three additional courses of chemotherapy. Subsequent MRI showed dramatic shrinkage of the left renal mass, resolution of the right atria1 tumor, resolution of the right renal lesion, and some residual irregular thickening of the IVC just superior to the left renal vein. Ultrasound confirmed most of the MRI findings but could not identify the residual IVC thickening. Eighteen weeks after treatment was begun, a right renal biopsy and a left radical nephrectomy were performed without difficulty. Palpation of the left renal vein and vena cava showed a firmness in their anterior walls. There was no tumor visible within the left renal vein. Frozen section of the renal vein thickening showed only scar tissue. Because of the tumor’s tremendous response to chemotherapy, the decision was made not to explore the vena cava. It was
Journalof Pediatric Surgery, Vol26, No 1 (January), 1991: pp64-67
INTRAVASCULAR
EXTENSION
OF WILMS’ TUMOR
65
metastatic disease and died 11 weeks after presentation. Autopsy showed a right 28 x 18 x 10 cm anaplastic Wilms’ tumor with complete renal vein and IVC occlusion. Multiple liver metastasis and bilateral lung metastasis were also present.
Case 3
Fig 1. Coronal MR image demonstrating dilated arygos and hemiazygos systems, intrahepatic WC occlusion (closed arrow), and a right atrial tumor thrombus (open arrow).
believed that further chemotherapy would likely resolve whatever minimal tumor tissue might be adherent to the wall of the vena cava. Pathological examination of the nephrectomy specimen demonstrated massive tumor necrosis and hyperplastic perilobar nephrogenic rests. No viable Wilms’ tumor was found. The right renal biopsy showed only perilobar nephrogenic rests. Because of the slight possibility of residual tumor within the IVC, she has received radiation therapy and two additional courses of chemotherapy as an outpatient. She currently is doing well and is without residual disease.
Case 2 This 5-year-old boy presented on December 19, 1987, with an H-month history of abdominal distention and intermittent pain. He experienced worsening of his abdominal pain just prior to presentation. Physical examination showed a pulse of 136 beats/mitt, blood pressure 130/94 mm Hg, respiration of 38 breathsimin, and temperature of 384°C. Avery distended, diffusely tender abdomen was also present. It was not possible to palpate an abdominal mass because of the tremendous distention. An abdominal series was suggestive of an abdominal mass. Chest x-ray showed a probable left pulmonary metastasis. CT scan showed a right abdominal mass of probable renal origin, which was approximately 18 x 10 cm in size. The liver was markedly displaced anteriorly and superiorly without evidence of metastatic disease. There was splaying and distortion of the renal pelvis and calyces, which was consistent with Wilms’ tumor. Also, there was a suggestion of tumor tissue within the renal vein, but the IVC could not be visualized because of distortion of the normal anatomy. Urinary catecholamines were negative. Ultrasound confirmed the right renal tumor with renal vein and IVC extension. However, the degree of cephalad tumor extension could not be determined. MRI confirmed a massive tumor arising from the upper pole of the right kidney and clearly demonstrated the cephalad extent of the vena caval tumor thrombus (Fig 2). MRI also clearly depicted the pulmonary metastasis that had been suspected on chest x-ray. Multiple needle biopsies were performed. Pathological examination showed anaplastic Wilms’ tumor. After 5 weeks of vincristine and actinomycin D, an ultrasound showed no significant tumor regression. Adriamycin was added to the chemotherapeutic regimen without any impact. He experienced unabated progressive
A 2-year-old boy was found to have a right-sided abdominal mass in March 1987. Physical examination demonstrated a large, smooth 10 x 10 cm right abdominal mass. Chest x-ray was clear. Family history showed that seven paternal cousins had had a Wilms’ tumor. Genetic evaluation of the patient and affected relatives was unremarkable. A CT scan of the abdomen showed a large tumor arising from the right kidney and a small medially located left renal mass. There was no apparent tumor extension into the right renal vein. Ultrasound identified the right renal tumor and the small left renal lesion, but also showed tumor tissue in the right renal vein. The IVC was free of tumor tissue. A needle biopsy of the right renal mass was performed and demonstrated Wilms’ tumor of favorable histological type. Because of apparent bilateral disease, chemotherapywith vincristine and actinomycin D was begun. Four weeks later a second CT scan showed significant shrinkage in the right renal tumor and no change in the left renal lesion. The renal vein and IVC were still shown to be tumor-free. Ultrasound also showed tumor shrinkage and no change in the left renal lesion. The renal vein still contained tumor by ultrasound. Ten weeks after the start of chemotherapy. MRI scan demonstrated a right renal tumor, renal vein involvement, and no IVC involvement. It also demonstrated a fetal lobulation of the left kidney. This finding prompted review of the prior CT scans and ultrasounds, which led to the revised opinion that a fetal lobulation, not a tumor, had been present all along. Twelve weeks after chemotherapy commenced, a right radical nephrectomy was performed. There was a small amount of tumor tissue present within the right renal vein. The IVC was free of tumor by palpation. The left kidney contained a fetal lobulation without any evidence of tumor. Pathology confirmed a 8 x 3 x 3 cm Wilms’ tumor of favorable histological type containing approximately 60% viable tumor. He did well postoperatively and was free of disease 18 months after surgery.
Fig 2. Coronal MR image of 5-year-old boy demonstrating a massive right renal tumor with renal vein (open arrow) and WC involvement (closed arrow).
66
WEESE, APPLEBAUM,
Case 4 This 3-year-old girl presented on February 8, 1987, with gross hematuria and intermittent abdominal pain. On physical examination there was a large, nontender left-sided abdominal mass. A CT scan showed a large tumor arising from the left kidney, which extended across the midline. It also showed renal vein and IVC tumor extension. Ultrasound confirmed the CT scan findings. The chest x-ray was clear. Transabdominal exploration showed a 8 x 12 cm tumor that enveloped the aorta. There was a palpable tumor within the IVC and no evidence of hepatic metastasis. The tumor was felt to be unresectable. Needle biopsy confirmed the diagnosis of Wilms’ tumor. Chemotherapy with vincristine and actinomycin D was begun postoperatively. Eight weeks later, after two courses of chemotherapy, a MRI scan showed tumor tissue within the renal vein and IVC plus necrosis within the left renal tumor. After completing a third course of chemotherapy, repeat MRI showed that the tumor was resectable. Transabdominal exploration was undertaken and a left radical nephrectomy was performed. Because there was a thin, cordlike structure palpable within the left renal vein and IVC up to the liver, proximal control of the IVC was gained via a median sternotomy. The IVC was opened and a friable, cordlike thrombus was found to be closely adherent to the wall. This thrombus shredded during attempted removal. The nephrectomy specimen showed extensive necrosis and Wilms’ tumor of favorable histological type. A small amount of viable tumor was present in the left renal vein. One year postoperatively, chest x-ray showed bilateral pulmonary nodules. Because these nodules were felt to represent metastatic Wilms’ tumor, chemotherapy was restarted. CT scan 3 months later demonstrated resolution of the right lung nodules but persistence of the left upper lung lesions. A left thoracotomy and partial upper lobectomy was performed. Pathological examination showed granulomatous disease. One year after the thoracotomy she is doing well. DISCUSSION
Commonly used studies for the diagnosis and follow-up of Wilms’ tumor are intravenous pyelography (IVP), vena cavography, ultrasound, CT, and MRI. Each of these studies has limitations in its ability to assess tumor extension. IVP is not very sensitive or specific in the evaluation of intravascular tumor extension, and may fail to show the intrarenal origin of a mass.6-8Vena cavography does not delineate the degree of cephalad tumor spread when complete obstruction of the IVC is present. It also has a high false-positive rate because crying increases intraabdominal pressure, resulting in filling of collateral veins despite a patent IVC.639Ultrasound’s main disadvantage is that it can be difficult to identify the origin of an abdominal mass or systematically image an entire mass.‘“‘ll CT has axial image limitations that often do not allow differentiation between an extrarenal or intrarenal lesion or visualization of a tumor thrombus within the renal vein or IVC.12.13MRI does not have the axial image limitations of CT, but it does require long exposure time, which necessitates sedation of pediatric patients.14
AND TABER
MRI, CT, and ultrasound were used to study each of the four patients. All were shown to have intravascular tumor extension. One had only renal vein involvement. Three had vena caval extension, with one of these having a massive intracardiac tumor thrombus. A comparison of the diagnostic accuracy of MRI, CT, and ultrasound was performed. It was found that CT clearly identified renal vein tumor in two of four patients and was accurate in diagnosing vena caval extension in only one of the three patients later shown to have IVC involvement. Ultrasound correctly diagnosed renal vein and IVC extension in all four cases, but did not accurately determine the cranial extent of the tumor thrombus. MRI was successful in delineating the true extent of intravascular spread in all cases. Although both ultrasound and MRI were able to correctly identify renal vein and IVC involvement, MRI’s image contrast and resolution was far superior. In addition, MRI was able to clearly depict the massive intracardiac tumor thrombus. Not only was MRI superior in delineating intravascular disease, but it also was able to conclusively identify unilateral disease and fetal lobulation in one patient after both ultrasound and CT had erroneously suggested bilateral disease. Knowing the true extent of disease spread preoperatively can have significant bearing on patient management. Based on the extent of disease, each of the patients reported received chemotherapy prior to operative intervention. Preoperative chemotherapy is currently a controversial topic in Wilms’ tumor management. Some authors recommend surgery as initial treatment in all patients.‘5’16Others recommend preoperative chemotherapy in selected patients such as those with bilateral disease, large unilateral tumor, vascular extension, or metastatic disease.“,” As was shown in the case reports, preoperative chemotherapy was successful in reducing the tumor burden in the three patients with favorable histology, but was unsuccessful in treating the patient with anaplastic Wilms’ tumor. We have found MRI to be superior to both ultrasound and CT for precisely determining the cranial extent of intravascular Wilms’ tumor and for delineating nonvascular disease. Because of its noninvasiveness, multiplane imaging capabilities, and excellent image contrast and resolution, MRI is ideal for the visualization of Wilms’ tumor. The superior diagnostic capabilities afforded by MRI allow the surgeon to better plan operative intervention and assess treatment options. We advocate the use of MRI in the diagnosis and follow-up of patients with intravascular Wilms’ tumor.
INTRAVASCULAR
EXTENSION
67
OF WILMS’ TUMOR
REFERENCES 1. Lattimer JK, Melicow MM, Uson report of 71 cases. J Urol80:401-416.1958
AC:
Wilms’
tumor:
A
2. Schullinger JN, Santulli TV, Casarella WJ, et al: Wilms’ tumor: The role of right heart angiography in the management of selected cases. Ann Surg 185:451-455,1977 3. Nakayama DK, deLorimier AA, O’Neill JA, et al: Intracardiac extension of Wilms’ tumor. Ann Surg 204:693-697,1986 4. Lemerle J, Tournade M, Gerard-Marchant tumor: Natural history and prognostic factors. 2566,1976
R, et al: Wilms’ Cancer 37:2557-
5. Leape LL, Breslow NE, Bishop HC: The surgical treatment of Wilms’ tumor: Results of the National Wilms Tumor Study. Ann Surg 187:351-356, 1978 6. Clayman RV. Sheldon CA, Gonzales R: Wilms’ tumor: An approach to vena caval intrusion. Prog Pediatr Surg 15:285-305, 1982 7. Luck SR, DeLeon S, Shkolnik tumor: Diagnosis and management, 1982
A, et al: Intracardiac Wilms’ J Pediatr Surg 17:551-554,
8. Canty TG. Hagaraj HS, Shearer LS: Nonvisualization of the intravenous pyelogram: A poor prognostic sign in Wilms’ tumor? J Pediatr Surg 14:825-830, 1979 9. Tucker
AS: The roentgen
diagnosis
of abdominal
masses
in
children: Intravenous urography vs. inferior venacavagraphy. AJR 95:76-90.1965 10. Kobrinsky NL, Talgoy M, Shuckett B. et al: Wilms’ tumor. Pediatr Ann 17:238-250,1988 11. Jaffe MH, White SJ, Silver TM, et al: Wilms’ tumor: Ultrasonic features, pathologic correlation and diagnostic pitfalls. Radiology 140:147-152, 1981 12. Currarino G: Renal neoplasms, in Silverman FN (ed): Caffey’s Pediatric X-Ray Diagnosis: An Integrated Imaging Approach. Chicago, IL, Year Book, 1985, pp 1639-1650 13. Kangarloo H, Dietrich RB, Ehrlich RM, et al: Magnetic resonance imaging of Wilms’ tumor. Urology 28:203-207,1986 14. LiPuma JP: Magnetic resonance imaging of the kidney. Radio1 Clin North Am 22:925-941,1984 15. Voute PA, Delemarre JFM, deKraker J: Preoperative therapy for Wilms’ tumor. Dial Pediatr Ural 11:5, 1988 16. Lemerle J, Voute PA, Tournade MF, et al: Effectiveness of preoperative chemotherapy in Wilms’ tumor: Results of an International Society of Paediatric Oncology (SIOP) clinical trial. J Clin Oncol 1:604-609. 1983 17. D’Angio GJ: Counterpoint: Preoperative therapy for Wilms’ tumor. Dial Pediatr Urol 11:5-6, 1988 18. Bracken RB, Sutow WW, Jaffe N, et al: Preoperative chemotherapy for Wilms’ tumor. Urology 19:55-60.1982
Intravascular Magnetic
Extension Resonance
By Donald L. Weese, Harry Applebaum, Los Angeles, l Accurate preoperative diagnosis of renal vein, vena caval, or intracardiac extension of Wilms’ tumor allows the surgeon to better plan operative vascular control and assess the potential benefits of preoperative chemotherapy. Magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound were used to study four consecutive patients presenting with Wilms’ tumor. Three had vena caval involvement, with one of these having a massive right atrial tumor thrombus. A fourth patient had renal vein involvement only. We found MRI to be superior to both CT and ultrasound for mapping intravascular extension of Wilms’ tumor and for delineating nonvascular disease. Because of its noninvasiveness, multiplane imaging capabilities, and image contrast and resolution, MRI is a valuable complimentary imaging modality for the diagnosis and follow-up of patients with Wilms’ tumor. Copyright o 1991 by W.B. Saunders Company INDEX WORDS: Wilms’ tumor, intravascular; nance imaging.
magnetic reso-
V
ASCULAR EXTENSION of Wilms’ tumor is a well known phenomenon. Renal vein involvement occurs in 15% to 20% of patients. Vena caval extension occurs in 5% to lo%, and intracardiac extension is reported in 0.5% to 1% of cases.‘-’ Intravascular involvement with Wilms’ tumor represents a significant challenge for the surgeon. The ability to remove a tumor thrombus intact without embolization can have direct bearing on patient management and prognosis; therefore, accurate preoperative diagnosis of vascular extension and careful planning of operative vascular control is essentia1.3r6.’ Traditional surgical management of caval involvement often required major vascular surgery, and cardiac tumor was optimally managed via atriotomy in conjunction with cardiopulmonary bypass3** Accurate information regarding tumor extension affords the surgeon the opportunity to consider the potential benefits of preoperative chemotherapy, which can sometimes eliminate the need for major vascular surgery. From the Depatiments of Surgery and Radiology, Kaiser Permanente Medical Center, Los Angeles, CA. Date accepted: February 20, 1990. Address reprint requests to Harry Applebaum, MD, Kaiser Permanente Medical Center, 1526 N Edgemont St, Los Angeles, CA 90027. Copyright o 1991 by WB. Saunders Company 0022-3468/9112601-OOI5$03.OOiO
64
of Wilms’ Tumor With Imaging and Paddy Taber
California
A variety of imaging studies have been used for the diagnosis and follow-up of intravascular Wilms’ tumor. A consensus opinion regarding which is the optimal study has not been reached. This paper compares the ability of magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound to assess vascular tumor extension in four consecutive patients presenting with Wilms’ tumor. CASE REPORTS Case 1 This 3-year-old girl presented to another facility on March 7, 1988, with abdominal pain and distension. Physical examination showed a pulse of 110 beatsimin, respiration 20 breathsimin, temperature 37.5”C, and blood pressure 100/76 mm Hg. A II/VI systolic ejection murmur and a large, smooth left abdominal mass were present. A CT scan of the abdomen was interpreted as showing a large left renal mass without vascular extension or suggestion of bilateral disease. However, retrospective analysis of the CT scan does suggest vascular extension and bilateral@. Ultrasound showed a left renal mass with renal vein involvement and inferiorvena cava (IVC) involvement. After the ultrasound the patient became tachycardiac and tachypneic and was transferred to this hospital for further evaluation. A two-dimensional echocardiogram was then obtained, which showed a massive right atrial tumor thrombus. An MRI confirmed the presence of a large left renal mass extending to the midline and a massive tumor thrombus that extended into the heart and occupied 90% of the right atrium. The MRI also showed complete subdiaphragmatic vena caval occlusion with dilated azygos and hemiazygos venous systems (Fig 1). A small lower pole right renal lesion was also visualized on MRI scan. Under ultrasonic guidance a needle biopsy of the renal mass was performed, which demonstrated Wilms’ tumor of favorable histological type. Chemotherapy with vincristine and actinomycin D was begun. During the first course of chemotherapy the patient’s tachycardia and tachypnea resolved. After the first course of chemotherapy echocardiography showed a significant decrease in the size of the atrial thrombus. Over 15 weeks she received three additional courses of chemotherapy. Subsequent MRI showed dramatic shrinkage of the left renal mass, resolution of the right atria1 tumor, resolution of the right renal lesion, and some residual irregular thickening of the IVC just superior to the left renal vein. Ultrasound confirmed most of the MRI findings but could not identify the residual IVC thickening. Eighteen weeks after treatment was begun, a right renal biopsy and a left radical nephrectomy were performed without difficulty. Palpation of the left renal vein and vena cava showed a firmness in their anterior walls. There was no tumor visible within the left renal vein. Frozen section of the renal vein thickening showed only scar tissue. Because of the tumor’s tremendous response to chemotherapy, the decision was made not to explore the vena cava. It was
Journalof Pediatric Surgery, Vol26, No 1 (January), 1991: pp64-67
INTRAVASCULAR
EXTENSION
OF WILMS’ TUMOR
65
metastatic disease and died 11 weeks after presentation. Autopsy showed a right 28 x 18 x 10 cm anaplastic Wilms’ tumor with complete renal vein and IVC occlusion. Multiple liver metastasis and bilateral lung metastasis were also present.
Case 3
Fig 1. Coronal MR image demonstrating dilated arygos and hemiazygos systems, intrahepatic WC occlusion (closed arrow), and a right atrial tumor thrombus (open arrow).
believed that further chemotherapy would likely resolve whatever minimal tumor tissue might be adherent to the wall of the vena cava. Pathological examination of the nephrectomy specimen demonstrated massive tumor necrosis and hyperplastic perilobar nephrogenic rests. No viable Wilms’ tumor was found. The right renal biopsy showed only perilobar nephrogenic rests. Because of the slight possibility of residual tumor within the IVC, she has received radiation therapy and two additional courses of chemotherapy as an outpatient. She currently is doing well and is without residual disease.
Case 2 This 5-year-old boy presented on December 19, 1987, with an H-month history of abdominal distention and intermittent pain. He experienced worsening of his abdominal pain just prior to presentation. Physical examination showed a pulse of 136 beats/mitt, blood pressure 130/94 mm Hg, respiration of 38 breathsimin, and temperature of 384°C. Avery distended, diffusely tender abdomen was also present. It was not possible to palpate an abdominal mass because of the tremendous distention. An abdominal series was suggestive of an abdominal mass. Chest x-ray showed a probable left pulmonary metastasis. CT scan showed a right abdominal mass of probable renal origin, which was approximately 18 x 10 cm in size. The liver was markedly displaced anteriorly and superiorly without evidence of metastatic disease. There was splaying and distortion of the renal pelvis and calyces, which was consistent with Wilms’ tumor. Also, there was a suggestion of tumor tissue within the renal vein, but the IVC could not be visualized because of distortion of the normal anatomy. Urinary catecholamines were negative. Ultrasound confirmed the right renal tumor with renal vein and IVC extension. However, the degree of cephalad tumor extension could not be determined. MRI confirmed a massive tumor arising from the upper pole of the right kidney and clearly demonstrated the cephalad extent of the vena caval tumor thrombus (Fig 2). MRI also clearly depicted the pulmonary metastasis that had been suspected on chest x-ray. Multiple needle biopsies were performed. Pathological examination showed anaplastic Wilms’ tumor. After 5 weeks of vincristine and actinomycin D, an ultrasound showed no significant tumor regression. Adriamycin was added to the chemotherapeutic regimen without any impact. He experienced unabated progressive
A 2-year-old boy was found to have a right-sided abdominal mass in March 1987. Physical examination demonstrated a large, smooth 10 x 10 cm right abdominal mass. Chest x-ray was clear. Family history showed that seven paternal cousins had had a Wilms’ tumor. Genetic evaluation of the patient and affected relatives was unremarkable. A CT scan of the abdomen showed a large tumor arising from the right kidney and a small medially located left renal mass. There was no apparent tumor extension into the right renal vein. Ultrasound identified the right renal tumor and the small left renal lesion, but also showed tumor tissue in the right renal vein. The IVC was free of tumor tissue. A needle biopsy of the right renal mass was performed and demonstrated Wilms’ tumor of favorable histological type. Because of apparent bilateral disease, chemotherapywith vincristine and actinomycin D was begun. Four weeks later a second CT scan showed significant shrinkage in the right renal tumor and no change in the left renal lesion. The renal vein and IVC were still shown to be tumor-free. Ultrasound also showed tumor shrinkage and no change in the left renal lesion. The renal vein still contained tumor by ultrasound. Ten weeks after the start of chemotherapy. MRI scan demonstrated a right renal tumor, renal vein involvement, and no IVC involvement. It also demonstrated a fetal lobulation of the left kidney. This finding prompted review of the prior CT scans and ultrasounds, which led to the revised opinion that a fetal lobulation, not a tumor, had been present all along. Twelve weeks after chemotherapy commenced, a right radical nephrectomy was performed. There was a small amount of tumor tissue present within the right renal vein. The IVC was free of tumor by palpation. The left kidney contained a fetal lobulation without any evidence of tumor. Pathology confirmed a 8 x 3 x 3 cm Wilms’ tumor of favorable histological type containing approximately 60% viable tumor. He did well postoperatively and was free of disease 18 months after surgery.
Fig 2. Coronal MR image of 5-year-old boy demonstrating a massive right renal tumor with renal vein (open arrow) and WC involvement (closed arrow).
66
WEESE, APPLEBAUM,
Case 4 This 3-year-old girl presented on February 8, 1987, with gross hematuria and intermittent abdominal pain. On physical examination there was a large, nontender left-sided abdominal mass. A CT scan showed a large tumor arising from the left kidney, which extended across the midline. It also showed renal vein and IVC tumor extension. Ultrasound confirmed the CT scan findings. The chest x-ray was clear. Transabdominal exploration showed a 8 x 12 cm tumor that enveloped the aorta. There was a palpable tumor within the IVC and no evidence of hepatic metastasis. The tumor was felt to be unresectable. Needle biopsy confirmed the diagnosis of Wilms’ tumor. Chemotherapy with vincristine and actinomycin D was begun postoperatively. Eight weeks later, after two courses of chemotherapy, a MRI scan showed tumor tissue within the renal vein and IVC plus necrosis within the left renal tumor. After completing a third course of chemotherapy, repeat MRI showed that the tumor was resectable. Transabdominal exploration was undertaken and a left radical nephrectomy was performed. Because there was a thin, cordlike structure palpable within the left renal vein and IVC up to the liver, proximal control of the IVC was gained via a median sternotomy. The IVC was opened and a friable, cordlike thrombus was found to be closely adherent to the wall. This thrombus shredded during attempted removal. The nephrectomy specimen showed extensive necrosis and Wilms’ tumor of favorable histological type. A small amount of viable tumor was present in the left renal vein. One year postoperatively, chest x-ray showed bilateral pulmonary nodules. Because these nodules were felt to represent metastatic Wilms’ tumor, chemotherapy was restarted. CT scan 3 months later demonstrated resolution of the right lung nodules but persistence of the left upper lung lesions. A left thoracotomy and partial upper lobectomy was performed. Pathological examination showed granulomatous disease. One year after the thoracotomy she is doing well. DISCUSSION
Commonly used studies for the diagnosis and follow-up of Wilms’ tumor are intravenous pyelography (IVP), vena cavography, ultrasound, CT, and MRI. Each of these studies has limitations in its ability to assess tumor extension. IVP is not very sensitive or specific in the evaluation of intravascular tumor extension, and may fail to show the intrarenal origin of a mass.6-8Vena cavography does not delineate the degree of cephalad tumor spread when complete obstruction of the IVC is present. It also has a high false-positive rate because crying increases intraabdominal pressure, resulting in filling of collateral veins despite a patent IVC.639Ultrasound’s main disadvantage is that it can be difficult to identify the origin of an abdominal mass or systematically image an entire mass.‘“‘ll CT has axial image limitations that often do not allow differentiation between an extrarenal or intrarenal lesion or visualization of a tumor thrombus within the renal vein or IVC.12.13MRI does not have the axial image limitations of CT, but it does require long exposure time, which necessitates sedation of pediatric patients.14
AND TABER
MRI, CT, and ultrasound were used to study each of the four patients. All were shown to have intravascular tumor extension. One had only renal vein involvement. Three had vena caval extension, with one of these having a massive intracardiac tumor thrombus. A comparison of the diagnostic accuracy of MRI, CT, and ultrasound was performed. It was found that CT clearly identified renal vein tumor in two of four patients and was accurate in diagnosing vena caval extension in only one of the three patients later shown to have IVC involvement. Ultrasound correctly diagnosed renal vein and IVC extension in all four cases, but did not accurately determine the cranial extent of the tumor thrombus. MRI was successful in delineating the true extent of intravascular spread in all cases. Although both ultrasound and MRI were able to correctly identify renal vein and IVC involvement, MRI’s image contrast and resolution was far superior. In addition, MRI was able to clearly depict the massive intracardiac tumor thrombus. Not only was MRI superior in delineating intravascular disease, but it also was able to conclusively identify unilateral disease and fetal lobulation in one patient after both ultrasound and CT had erroneously suggested bilateral disease. Knowing the true extent of disease spread preoperatively can have significant bearing on patient management. Based on the extent of disease, each of the patients reported received chemotherapy prior to operative intervention. Preoperative chemotherapy is currently a controversial topic in Wilms’ tumor management. Some authors recommend surgery as initial treatment in all patients.‘5’16Others recommend preoperative chemotherapy in selected patients such as those with bilateral disease, large unilateral tumor, vascular extension, or metastatic disease.“,” As was shown in the case reports, preoperative chemotherapy was successful in reducing the tumor burden in the three patients with favorable histology, but was unsuccessful in treating the patient with anaplastic Wilms’ tumor. We have found MRI to be superior to both ultrasound and CT for precisely determining the cranial extent of intravascular Wilms’ tumor and for delineating nonvascular disease. Because of its noninvasiveness, multiplane imaging capabilities, and excellent image contrast and resolution, MRI is ideal for the visualization of Wilms’ tumor. The superior diagnostic capabilities afforded by MRI allow the surgeon to better plan operative intervention and assess treatment options. We advocate the use of MRI in the diagnosis and follow-up of patients with intravascular Wilms’ tumor.
INTRAVASCULAR
EXTENSION
67
OF WILMS’ TUMOR
REFERENCES 1. Lattimer JK, Melicow MM, Uson report of 71 cases. J Urol80:401-416.1958
AC:
Wilms’
tumor:
A
2. Schullinger JN, Santulli TV, Casarella WJ, et al: Wilms’ tumor: The role of right heart angiography in the management of selected cases. Ann Surg 185:451-455,1977 3. Nakayama DK, deLorimier AA, O’Neill JA, et al: Intracardiac extension of Wilms’ tumor. Ann Surg 204:693-697,1986 4. Lemerle J, Tournade M, Gerard-Marchant tumor: Natural history and prognostic factors. 2566,1976
R, et al: Wilms’ Cancer 37:2557-
5. Leape LL, Breslow NE, Bishop HC: The surgical treatment of Wilms’ tumor: Results of the National Wilms Tumor Study. Ann Surg 187:351-356, 1978 6. Clayman RV. Sheldon CA, Gonzales R: Wilms’ tumor: An approach to vena caval intrusion. Prog Pediatr Surg 15:285-305, 1982 7. Luck SR, DeLeon S, Shkolnik tumor: Diagnosis and management, 1982
A, et al: Intracardiac Wilms’ J Pediatr Surg 17:551-554,
8. Canty TG. Hagaraj HS, Shearer LS: Nonvisualization of the intravenous pyelogram: A poor prognostic sign in Wilms’ tumor? J Pediatr Surg 14:825-830, 1979 9. Tucker
AS: The roentgen
diagnosis
of abdominal
masses
in
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