MAGNETIC RESONANCE IMAGING OF CYSTIC, PARTIALLY DIFFERENTIATED NEPHROBLASTOMA O. E. ABARA, M.D. R LIU, M.D. B. M. C H U R C H I L L , M.D. K. MANCER, M.D. From the Division of Urology, Departments of Surgery, Radiology and Pathology, Hospital for Sick Children, Toronto, Canada
ABSTRACT--The magnetic resonance imaging (MRI) appearance of a cystic, partially differen-; tiated nephroblastoma is described, together with pathologic correlation. The difficulty in reaching a correct preoperative diagnosis even with multimodal imaging techniques is emphasized. MRI is an adjunct to ultrasonography and may be superior to computerized tomography (CT) scan in the evaluation of a child with multiloculated cystic renal mass.
Cystic, partially differentiated nephroblastoma is one of the two most common multiloeulated renal masses in children. To our knowledge, the appearance of this lesion on magnetic resonance imaging (MRI) has not been described in the English literature. We recently have assessed a seven and one-half-month-old boy w i t h a multiloculated left renal mass, which pathologically proved to be a cystic, partially differentiated nephroblastoma. We report the appearance of this lesion on MRI together with the pathologic correlation.
lecting system. An abdominal ultrasound dem, onstrated a 12 cm x 10 cm x 10 cm multilocu~ lated cystic mass in the upper half of the leff kidney, with some residual normal renal tissu6 in the lower pole (Fig. 1). Moderately thick sepi rations were present along the posterior aspect of this mass. No solid component was seen. Th~ remainder of the abdomen, including right kidi ney, inferior vena eava, and liver, was normall
Case Report A seven and one-half-month-old male infant was referred because of a swelling on the left side of the abdomen that was discovered on routine medical examination. On physical examination, the patient had a non-tender, firm 10 x 10 cm mass on the left side of the abdomen. The child otherwise was healthy. The laboratory tests, including complete blood count, urinalysis, and biochemical renal function tests were normal. A vanillylmandelic acid (VMA) screening test was negative. The excretory urogram showed a large mass arising from the upper half of the left kidney, associated with distortion of the adjacent col-
424
UROLO,
RE 2. CT scan oJ multiloculated cystic mass; compressed remnant of normal renal tissue posfly (white arrow).
Computerized tomography (CT) scan eonirmed sonographic findings, and showed a veil-encapsulated multiloculated mass in the ~ft kidney (Fig. 2). The cystic spaces were of 'affable size and shape, and had CT attenuaion values of about 10 to 20 HU, similar to that !f water. No enhancement of the septations or he cystic contents was evident following inravenous contrast enhancement. CT scan of he chest and abdomen also showed no evidence pfmetastasis.
A multislice spin-echo technique was used for the MRI examination (General Electric 1.5T Signa imaging system), and the images were obtained in both axial and coronal planes (Fig. 3A and B). MRI examination revealed similar anatomic findings of a multiseptated mass lesion in the left kidney, and the T1 (600/20) and T2 (2,000/35, 2,000/70) weighted sequences also suggested the fluid nature of the lesion. In addition, the MRI showed different signal intensities from the various compartments of the multiloculated lesion, although the absolute relaxation values were not measured for the study. The remainder of the intra-abdominal organs, including the liver, appeared to be normal. The aorta and inferior vena cava were displaced to the right by the mass effect, but were still patent. The child had a left nephrectomy. At laparotomy, the left kidney was almost completely replaced by a firm, lobulated, avascular tumor extending from the left flank across the midline. The left renal pelvis and ureter, though compressed by the tumor, appeared to be normal. The right kidney, liver, spleen, and para-aortic lymph nodes and the great vessels were normal. The kidney weighed 273 g, and its upper and middle portions were occupied by a multilocular mass measuring 10 x 10 x 8 cm. The renal vessels, segment of the ureter, and renal pelvis
n~ure oJ multi-septateclcystic mass. Higher signal'intensities shown in 2 components, suggestfluid contents. Compressed remnant of normal renal tissue shown posteriorly (white arrow). t arrow) and inferior vena cava (open arrow) displaced to right, but still patent. (B) Coronal 10/20) weighted sequence, shows relationship of mass to adjacent organs (L = liver, B = bladow = IVC).
NOVEMBER1990 / VOLUMEXXXVI,NUMBER5
425
FIGURE 4. Cut surface of bisected nephrectomy specimen shows rounded multicystic lesion with residual renal tissue at periphery. Fibrous septae of variable thickness separate cyst. were unremarkable. Gross specimen revealed an encapsulated, multicystic tumor with numerous thin trabecula separating the individual cysts (Fig. 4). The cysts ranged from 0.2 to 2.5 cm in diameter, had smooth inner surfaces, and contained a clear yellow fluid. No blood or old hematoma was noted. There was a rim of renal parenchyma compressed by the tumor. Histologically, the lesion was composed of variably sized cysts lined with cuboidal epithelium and surrounded by a stroma that was largely fibrous and myxoid but which contained loci of nephrogenic blastema, immature tubules, and i m m a t u r e glomeruli similar to those seen in classic Wilms tumor. The appearance of the immature tubules ranged from microscopic-sized cystic structures to macroscopic cysts as a continuum. Also present in the trabecula were loci of adipose tissue and striated muscle. The m u l t i l o c u l a r cystic lesion was surrounded by a pseudocapsule of compressed renal parenchyma similar to that found in association with most of Wilms tumor. There was no evidence of contiguous extension, vascular or lymphatic invasion. Convalescence was uneventful, and thirty months postoperatively the child remains well and free of disease. Comment Multiloculated cystic renal neoplasms are rare; the simple multilocular cyst (SMC) and the cystic partially differentiated nephroblast o m a ( C P D N ) are t h e m o s t c o m m o n in children. I The criteria for simple multiloeular cyst as defined in 1956 by Boggs and Kimmel-
426
stiel 2 include: (1) the lesion mus lar; (2) the cyst must be noncomJ the cyst must for the most pa epithelium; (4) the residual ren; be essentially normal except foa phy; and (5) fully developed n~ tions of such should not be pre: septa of the cystic lesion. The logic features of the cystic par tiated nephroblastoma are sirr multilocular cyst except for the ence of less differentiated (Wil elements in the stroma of the c neoplasm is more common in ally occurs at a younger age tZ multilocular cyst and c l a s s i c With surgical removal, the prc lent. Several reports describe the nance imaging of various well-t sions, including classic Wilms t~ ports have c o m p a r e d magnc imaging with other modalities. ~ We have not been able to find the appearance of cystic, par tiated nephroblastoma (polycy mor) on MRI in the literature. 4 MRI was able to delineate the re sitely and showed similar anat the sonographic and CT examir the multiple strands within the mass were better shown on the 1~ CT examination. In addition, t showed the signal intensities of tl partments to be different, sugg contents in the various areas c bleeding into a loculated comp occur in a multiloculated lesio~ Wilms tumor or polycystic dise ney, MRI would potentially sho intensity from the involved col evidence of bleeding was noted and the higher signal intensity J compartments was probably d fluid contents. The capability of MRI in dir, sagittal planes is also useful i n anatomic perspective of the le The overall size of the mass and to the adjacent organs sometim~ appreciated in a coronal format "overall picture" is a disadvant~ graphic hard-copy images, alth~ actually doing sonographic e~ well appreciate the lesion and it
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mt organs. With MRI, the lack of raan added advantage in the pediatric ~, especially if follow-up examinations red. ain differential diagnosis is simple lar cyst, and radiologie differentiation t. CPDN may have thicker septations have solid components within the lated lesion. Nephreetomy is required ,~malignancy with confidence, and the for both of these cystic tumors is exter nephreetomy. mary, MRI was able to provide similar information as did the CT and sono~xaminations. In addition, the ability in multiple planes and the potential to difference in contents of the various fluid compartments are unique. The diation is also a benefit to the pediatric We recommend sonography as the inining modality, and this case suggests i has the potential to replace CT scan nent of a multiloculated cystic renal
We share the views of others a,s that the excellent prognosis in this neoplasm does not preclude careful follow-up. 555 U n i v e r s i t y A v e n u e Toronto, O n t a r i o , C a n a d a M 5 G 1X8
(DR. LIU) tle£erenoes 1. Hartman DS, Davis CJ, Sanders RC, and John TT: The multiloculated renal masses: consideration and differential features, Radiographs 7:9.9 (1987). 2. Boggs LK, and Kimmelstiel P: Benign multiloeular cystic nephroma. Report of two eases of so-called multflocular cyst of the kidney, J Urol 76:530 0956). 3. Joshi VV, Banerjee AK, Yadav K, and Pathak IC: Cystic partially differentiated nephroblastoma: a elinieopathologic entity in the spectrum of infantile renal neoplasia, Cancer 40:789 (1977). 4. Christ ML: Polyeystie nephroblastoma, J Urol 98:570
(1968). 5. Leung AWL, et ah Magnetic resonance imaging of the kidneys, AJR 143:1215 (1984). 6. Choyke PL, et al: Focal renal masses: magnetic resonance imaging, Radiology 152:471 (1984). 7. Dietrich RB, and Kangarloo H: Kidneys in infants and children: evaluation with MRI, Radiology 159:215 (1986). 8. Madwell JE, et al: Multilocular cystic nephroma: a radiologic-pathologic correlation of 58 patients, Radiology 46:309
(1983).
UROLOGY / NOVEMBER 1990 / VOLUMEXXXVI, NUMBER 5
427
ABSTRACT--The magnetic resonance imaging (MRI) appearance of a cystic, partially differen-; tiated nephroblastoma is described, together with pathologic correlation. The difficulty in reaching a correct preoperative diagnosis even with multimodal imaging techniques is emphasized. MRI is an adjunct to ultrasonography and may be superior to computerized tomography (CT) scan in the evaluation of a child with multiloculated cystic renal mass.
Cystic, partially differentiated nephroblastoma is one of the two most common multiloeulated renal masses in children. To our knowledge, the appearance of this lesion on magnetic resonance imaging (MRI) has not been described in the English literature. We recently have assessed a seven and one-half-month-old boy w i t h a multiloculated left renal mass, which pathologically proved to be a cystic, partially differentiated nephroblastoma. We report the appearance of this lesion on MRI together with the pathologic correlation.
lecting system. An abdominal ultrasound dem, onstrated a 12 cm x 10 cm x 10 cm multilocu~ lated cystic mass in the upper half of the leff kidney, with some residual normal renal tissu6 in the lower pole (Fig. 1). Moderately thick sepi rations were present along the posterior aspect of this mass. No solid component was seen. Th~ remainder of the abdomen, including right kidi ney, inferior vena eava, and liver, was normall
Case Report A seven and one-half-month-old male infant was referred because of a swelling on the left side of the abdomen that was discovered on routine medical examination. On physical examination, the patient had a non-tender, firm 10 x 10 cm mass on the left side of the abdomen. The child otherwise was healthy. The laboratory tests, including complete blood count, urinalysis, and biochemical renal function tests were normal. A vanillylmandelic acid (VMA) screening test was negative. The excretory urogram showed a large mass arising from the upper half of the left kidney, associated with distortion of the adjacent col-
424
UROLO,
RE 2. CT scan oJ multiloculated cystic mass; compressed remnant of normal renal tissue posfly (white arrow).
Computerized tomography (CT) scan eonirmed sonographic findings, and showed a veil-encapsulated multiloculated mass in the ~ft kidney (Fig. 2). The cystic spaces were of 'affable size and shape, and had CT attenuaion values of about 10 to 20 HU, similar to that !f water. No enhancement of the septations or he cystic contents was evident following inravenous contrast enhancement. CT scan of he chest and abdomen also showed no evidence pfmetastasis.
A multislice spin-echo technique was used for the MRI examination (General Electric 1.5T Signa imaging system), and the images were obtained in both axial and coronal planes (Fig. 3A and B). MRI examination revealed similar anatomic findings of a multiseptated mass lesion in the left kidney, and the T1 (600/20) and T2 (2,000/35, 2,000/70) weighted sequences also suggested the fluid nature of the lesion. In addition, the MRI showed different signal intensities from the various compartments of the multiloculated lesion, although the absolute relaxation values were not measured for the study. The remainder of the intra-abdominal organs, including the liver, appeared to be normal. The aorta and inferior vena cava were displaced to the right by the mass effect, but were still patent. The child had a left nephrectomy. At laparotomy, the left kidney was almost completely replaced by a firm, lobulated, avascular tumor extending from the left flank across the midline. The left renal pelvis and ureter, though compressed by the tumor, appeared to be normal. The right kidney, liver, spleen, and para-aortic lymph nodes and the great vessels were normal. The kidney weighed 273 g, and its upper and middle portions were occupied by a multilocular mass measuring 10 x 10 x 8 cm. The renal vessels, segment of the ureter, and renal pelvis
n~ure oJ multi-septateclcystic mass. Higher signal'intensities shown in 2 components, suggestfluid contents. Compressed remnant of normal renal tissue shown posteriorly (white arrow). t arrow) and inferior vena cava (open arrow) displaced to right, but still patent. (B) Coronal 10/20) weighted sequence, shows relationship of mass to adjacent organs (L = liver, B = bladow = IVC).
NOVEMBER1990 / VOLUMEXXXVI,NUMBER5
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FIGURE 4. Cut surface of bisected nephrectomy specimen shows rounded multicystic lesion with residual renal tissue at periphery. Fibrous septae of variable thickness separate cyst. were unremarkable. Gross specimen revealed an encapsulated, multicystic tumor with numerous thin trabecula separating the individual cysts (Fig. 4). The cysts ranged from 0.2 to 2.5 cm in diameter, had smooth inner surfaces, and contained a clear yellow fluid. No blood or old hematoma was noted. There was a rim of renal parenchyma compressed by the tumor. Histologically, the lesion was composed of variably sized cysts lined with cuboidal epithelium and surrounded by a stroma that was largely fibrous and myxoid but which contained loci of nephrogenic blastema, immature tubules, and i m m a t u r e glomeruli similar to those seen in classic Wilms tumor. The appearance of the immature tubules ranged from microscopic-sized cystic structures to macroscopic cysts as a continuum. Also present in the trabecula were loci of adipose tissue and striated muscle. The m u l t i l o c u l a r cystic lesion was surrounded by a pseudocapsule of compressed renal parenchyma similar to that found in association with most of Wilms tumor. There was no evidence of contiguous extension, vascular or lymphatic invasion. Convalescence was uneventful, and thirty months postoperatively the child remains well and free of disease. Comment Multiloculated cystic renal neoplasms are rare; the simple multilocular cyst (SMC) and the cystic partially differentiated nephroblast o m a ( C P D N ) are t h e m o s t c o m m o n in children. I The criteria for simple multiloeular cyst as defined in 1956 by Boggs and Kimmel-
426
stiel 2 include: (1) the lesion mus lar; (2) the cyst must be noncomJ the cyst must for the most pa epithelium; (4) the residual ren; be essentially normal except foa phy; and (5) fully developed n~ tions of such should not be pre: septa of the cystic lesion. The logic features of the cystic par tiated nephroblastoma are sirr multilocular cyst except for the ence of less differentiated (Wil elements in the stroma of the c neoplasm is more common in ally occurs at a younger age tZ multilocular cyst and c l a s s i c With surgical removal, the prc lent. Several reports describe the nance imaging of various well-t sions, including classic Wilms t~ ports have c o m p a r e d magnc imaging with other modalities. ~ We have not been able to find the appearance of cystic, par tiated nephroblastoma (polycy mor) on MRI in the literature. 4 MRI was able to delineate the re sitely and showed similar anat the sonographic and CT examir the multiple strands within the mass were better shown on the 1~ CT examination. In addition, t showed the signal intensities of tl partments to be different, sugg contents in the various areas c bleeding into a loculated comp occur in a multiloculated lesio~ Wilms tumor or polycystic dise ney, MRI would potentially sho intensity from the involved col evidence of bleeding was noted and the higher signal intensity J compartments was probably d fluid contents. The capability of MRI in dir, sagittal planes is also useful i n anatomic perspective of the le The overall size of the mass and to the adjacent organs sometim~ appreciated in a coronal format "overall picture" is a disadvant~ graphic hard-copy images, alth~ actually doing sonographic e~ well appreciate the lesion and it
UROLOGY
/
N O V E M B E R 1990
/
VOLUME
mt organs. With MRI, the lack of raan added advantage in the pediatric ~, especially if follow-up examinations red. ain differential diagnosis is simple lar cyst, and radiologie differentiation t. CPDN may have thicker septations have solid components within the lated lesion. Nephreetomy is required ,~malignancy with confidence, and the for both of these cystic tumors is exter nephreetomy. mary, MRI was able to provide similar information as did the CT and sono~xaminations. In addition, the ability in multiple planes and the potential to difference in contents of the various fluid compartments are unique. The diation is also a benefit to the pediatric We recommend sonography as the inining modality, and this case suggests i has the potential to replace CT scan nent of a multiloculated cystic renal
We share the views of others a,s that the excellent prognosis in this neoplasm does not preclude careful follow-up. 555 U n i v e r s i t y A v e n u e Toronto, O n t a r i o , C a n a d a M 5 G 1X8
(DR. LIU) tle£erenoes 1. Hartman DS, Davis CJ, Sanders RC, and John TT: The multiloculated renal masses: consideration and differential features, Radiographs 7:9.9 (1987). 2. Boggs LK, and Kimmelstiel P: Benign multiloeular cystic nephroma. Report of two eases of so-called multflocular cyst of the kidney, J Urol 76:530 0956). 3. Joshi VV, Banerjee AK, Yadav K, and Pathak IC: Cystic partially differentiated nephroblastoma: a elinieopathologic entity in the spectrum of infantile renal neoplasia, Cancer 40:789 (1977). 4. Christ ML: Polyeystie nephroblastoma, J Urol 98:570
(1968). 5. Leung AWL, et ah Magnetic resonance imaging of the kidneys, AJR 143:1215 (1984). 6. Choyke PL, et al: Focal renal masses: magnetic resonance imaging, Radiology 152:471 (1984). 7. Dietrich RB, and Kangarloo H: Kidneys in infants and children: evaluation with MRI, Radiology 159:215 (1986). 8. Madwell JE, et al: Multilocular cystic nephroma: a radiologic-pathologic correlation of 58 patients, Radiology 46:309
(1983).
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427
