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Perinephric Fluid Collections Due to Renal Lymphangiectasia
Imaging Teaching Case Perinephric Fluid Collections Due to Renal Lymphangiectasia Nisar A. Wani, MD,1 Tasleem Kosar, DMRD,1 Tariq Gojwari, MD,1 and Umar A. Qureshi, MD2 Fluid collections around the kidneys on cross-sectional imaging may be caused by urine, blood, pus, lymph, or plasma. Ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) can not only show and characterize the fluid, but also may help determine the underlying cause of the perinephric fluid collection, such as ureteric obstruction, kidney injury, infection, or renal lymphangiectasia. Renal lymphangiectasia is characterized by abnormal and ectatic lymphatic vessels within and around the kidneys. Dilated lymphatics may result in peripelvic cysts (intrarenal lymphangiectasia) and perinephric fluid collections (extrarenal lymphangiectasia), which can be visualized using US, CT, and MRI. Proper diagnosis on imaging helps in planning a conservative management approach to this benign condition, which requires intervention for only significant symptoms or complications. We describe a 60-year-old man with normal kidney function and bilateral perinephric fluid collections in whom renal lymphangiectasia was diagnosed noninvasively on the basis of characteristic findings on US, CT, and MRI. Am J Kidney Dis. 57(2):347-351. © 2011 by the National Kidney Foundation, Inc. INDEX WORDS: Renal lymphangiectasia; peripelvic cyst; perinephric fluid collection.
INTRODUCTION Fluid collections may form around the kidneys in various pathologic conditions. Imaging using ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) may help identify the fluid and localizes the collection with respect to subcapsular, perirenal, or pararenal spaces. A combination of clinical features in conjunction with radiologic findings on cross-sectional imaging helps determine the nature of fluid collection, including urinoma, hematoma, or abscess.1 Postoperative lymphocele/ fluid collections may form around the kidneys after transplant. Sometimes lymphatic fluid may collect in the form of lymphangiomas in various parts of the body caused by defective development and communication of lymphatics. Renal involvement by this lymphatic space dilatation, called lymphangiectasia, may result in peripelvic renal cyst formation and/or fluid collections around the kidneys.2
CASE REPORT Clinical History and Initial Laboratory Data A 60-year-old man presented with concerns of breathlessness and fatigue for the last month. Other than smoking, he had no relevant medical history. On examination, he was pale, pulse was 90 beats/min, and blood pressure was 130/86 mm Hg. Heart and lungs were normal, and lymphadenopathy was absent. On abdominal examination, soft ballotable swelling was palpable in the right lumbar region and right renal angle. Mild splenomegaly was present. Routine blood investigations showed the following values: hemoglobin, 8 g/dL (80 g/L) with microcytic hypochromic picture; total leukocyte count, 8 ⫻103/L (8 ⫻109/L); and platelet count, 350 ⫻103/L (350 ⫻109/L). Urinalysis had normal results, with no significant proteinuria, red blood cells, or casts in urine. Serum chemistry tests showed the following values: sodium, 140 mEq/L (140 mmol/L); potassium, 4.2 mEq/L (4.2 mmol/L); calAm J Kidney Dis. 2011;57(2):347-351
cium, chloride, and bicarbonate also were within the reference ranges; serum urea nitrogen, 31 mg/dL (11.06 mmol/L); and serum creatinine, 1.1 mg/dL (97.24 mol/L), with estimated glomerular filtration rate of 73 mL/min/1.73 m2 (1.22 mL/s/1.73 m2). Serum albumin, total cholesterol, blood glucose (fasting), and liver function test results were unremarkable. Serum iron and ferritin levels were low, and total iron-binding capacity and erythropoietin level were increased. Stool examination for occult blood was negative. Upper- and lower-gastrointestinal endoscopic examinations did not show a pathologic state.
Imaging Studies Transabdominal US with a curvilinear transducer showed a large anechoic fluid collection without septations around the right kidney, displacing the kidney anteriorly. The right kidney appeared bright in echotexture because of through transmission from the surrounding fluid; size and corticomedullary differentiation were normal. No hydronephrosis, calculus, or cyst was seen in the kidney. The left kidney was surrounded by multiple variable-sized anechoic fluid collections with intervening septations without debris (Fig 1). The underlying kidney was normal in size and corticomedullary differentiation without hydronephrosis or mass lesion. There was no free fluid in the peritoneal cavity. CT was performed using multidetector-row CT after intravenous injection of iodinated contrast, which showed a large homogenous hypodense (0-10 HU [Hounsfield units]) fluid collection around the bilateral kidneys predominant on the posterior aspects. Fluid
From the Departments of 1Radiodiagnosis and Imaging and Pediatrics, Sher-I-Kashmir Institute of Medical Sciences, Srinagar, India. Received April 9, 2010. Accepted in revised form June 30, 2010. Originally published online October 1, 2010. Address correspondence to Nisar A. Wani, MD, Department of Radiodiagnosis and Imaging, Sher-I-Kashmir Institute of Medical Sciences (SKIMS), Srinagar 190011, India. E-mail: ahmad77chinar@ hotmail.com © 2011 by the National Kidney Foundation, Inc. 0272-6386/$36.00 doi:10.1053/j.ajkd.2010.06.028
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Figure 1. Ultrasound image of the kidneys shows a large anechoic collection displacing and compressing the right kidney (rightward arrow); the left kidney is surrounded by multiseptate anechoic fluid collection (leftward arrow). The renal cortex of the kidneys is separate and away from the cyst and fluid collection and shows a bright echopattern due to through transmission via the surrounding fluid.
collection was larger around the right kidney, displacing it anteriorly; no septations were seen in the perirenal collections. A thin fluid collection was visualized around the aorta and inferior vena cava in the midline retroperitoneum; no intrarenal cyst, collection, or hydronephrosis was seen; and sinus fat was prominent (Fig 2A). Both kidneys showed normal excretion of contrast into the nondilated pelvicaliceal system, which did not communicate with the perinephric fluid (Fig 2B). MRI showed the perirenal fluid collection as homogenously hypointense on T1-weighted and hyperintense on T2-weighted sequences, suggesting simple fluid. No septations were seen in the right perirenal collection, whereas the left-sided collection was composed of multiple thin-walled cysts of variable size separate from the renal cortex. Kidneys appeared normal in size, and signal intensity without intraparenchymal cysts or hydronephrosis (Fig 3A and B).
Diagnosis Perinephric fluid collections due to renal lymphangiectasia.
Clinical Follow-up The patient was started on oral iron therapy for the symptomatic iron deficiency anemia. US-guided aspiration of the fluid was performed for cytologic evaluation, which showed a leukocyte count of 40 cells/L with predominant (90%) lymphocytes and protein level of
0.6 g/dL (6 g/L). No bacteria could be stained or cultured from the aspirate. The patient was advised to undergo serial kidney function tests and imaging follow-up.
DISCUSSION Renal lymphangiectasia is a benign disease of renal lymphatics, also known as renal lymphangiomatosis, renal lymphangiomas, peripelvic lymphangiectasia, and renal peripelvic multicystic lymphangiectasia. Because this disorder is characterized by ectasia of the peripelvic, perirenal, and intrarenal lymphatic vessels, the term renal lymphangiectasia is preferred.3 Abnormal dilatation of these lymphatic ducts arises from their failure of communication with larger retroperitoneal lymph vessels. This may be a congenital abnormality or a gradually progressive acquired dysfunction of lymphatics. Although usually bilateral, renal lymphangiectasia may be unilateral or focal.4 Dilated lymphatics more commonly may appear inside kidneys in the peripelvic area, resulting in intrarenal
Figure 2. (A) Transverse computed tomographic image in the nephrographic phase shows a perirenal fluid attenuation collection posterior to the right kidney, displacing it anteriorly (left upward arrow); a smaller collection is seen around the left kidney, which is in place (right upward arrow). Thinner fluid attenuation is seen in the midline around the aorta and inferior vena cava in the retroperitoneum (downward arrow). The renal cortex is separate from the fluid. (B) Coronal reformat computed tomography in the excretory phase shows bilateral perirenal fluid attenuation with normal underlying renal parenchyma (upward arrows). The pelvicaliceal system outlined by the excreted contrast is not dilated and sinus fat is prominent in both kidneys (downward arrows). 348
Am J Kidney Dis. 2011;57(2):347-351
Renal Lymphangiectasia
Figure 3. (A) T2-weighted axial magnetic resonance image shows a homogenous hyperintense signal intensity perirenal collection around the right kidney, posteriorly displacing it (downward arrow); the left kidney is surrounded by multiple variable-sized similar hyperintense signal intensity cysts posteriorly and laterally (upward arrow). The renal cortex is well separated from the cysts and fluid collection and shows normal signal intensity. (B) Coronal T2-weighted magnetic resonance image shows perirenal homogenous hyperintense (fluid) signal intensity in the form of multiple cysts around the left kidney (leftward arrow) and a larger collection around the right kidney (downward arrow). Kidneys appear normal in size.
lymphangiectasia, or less commonly in the perinephric tissue, resulting in extrarenal lymphangiectasia.5 Usually seen in children, isolated or predominant involvement of small renal parenchymal lymphatics may result in bilateral nephromegaly. Thin small fluid collections may form in the midline retroperitoneum around the aorta and inferior vena cava.5,6 Dilatation of larger peripelvic lymph channels results in peripelvic cysts, seen in the general population. Another name for peripelvic cysts is intrarenal lymphangiectasia. Peripelvic cysts are easy to detect by means of US and CT because of their position in the renal sinus.7 Although their flat fanlike shape may distinguish them from the more common cortical cysts, they may
be confused with hydronephrosis (Fig 4A).7 The lack of communication between the individual cystic components and the pelvicaliceal system in the excretory phase of contrast-enhanced CT and MRI suggests the diagnosis of intrarenal lymphangiectasia (Fig 4B). The complete picture of renal lymphangiectasia resulting in a combination of peripelvic cysts and perinephric cysts is an unusual entity that has a characteristic appearance on imaging.3 Renal lymphangiectasia may present at any age, with equal involvement in men and women. Patients may present with abdominal distension, flank pain, or abdominal lump. It also may present as an incidental finding in patients with unrelated symptoms. Hyperten-
Figure 4. (A) Ultrasound image of a kidney shows multiple noncommunicating anechoic lesions representing peripelvic cysts (arrows) in a case of intrarenal lymphangiectasia; hydronephrosis is a close differential diagnosis. (B) Contrast-enhanced transverseplane computed tomographic image in the excretory phase shows fluid attenuation areas (arrows) around the contrast-outlined pelvicaliceal system in a case of intrarenal lymphangiectasia with more prominent peripelvic cysts in the left kidney. Am J Kidney Dis. 2011;57(2):347-351
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sion, hematuria, proteinuria, renal vein thrombosis, and ureteric obstruction have been reported in patients with renal lymphangiectasia.7,8 Extrinsic compression of the kidneys may alter kidney function or result in Page kidney. Perirenal lymphangiomas may be complicated by hemorrhage. Marked expansion of the perirenal fluid collection and development of ascites may be exacerbated by pregnancy.2,9 Before the advent of modern cross-sectional imaging modalities, the diagnosis of renal lymphangiectasia was made after exploratory laparotomy or nephrectomy. Although intravenous pyelography may show distortion of the pelvicaliceal system by the intrapelvic or perinephric cysts, this finding is nonspecific. Findings of US, CT, and MRI are characteristic of renal lymphangiectasia.5,10-14 Noninvasive diagnosis can be accomplished in most cases using US, with CT required in some cases. US shows the dilated lymphatic vessel as anechoic multiseptate thin-walled fluid collections (cysts) with posterior acoustic enhancement in the peripelvic and perirenal locations. Sometimes larger fluid collections without septations may form around the kidney, compressing and displacing it. Kidneys may be normal sized or enlarged, and renal echogenicity may be increased with the corticomedullary differentiation altered.5,6,10 Renal lymphangiectasia on CT is seen as nonenhancing hypodense attenuation (0-10 HU) collections around bilateral kidneys and in the peripelvic region. Intervening septations may or may not be visualized. CT enhances the demonstration of pelvic, peripelvic, and perirenal cysts and their relationship with the renal vessels and parenchyma, and computed tomographic urography allows delineation of the pelvicaliceal system. Associated smaller and thinner fluid collections around the aorta and inferior vena cava in the retroperitoneum are shown better using CT.5,6,8,10-12 MRI confirms the fluid nature in peripelvic and perirenal cysts and collections from the homogenous hypointense signal intensity on T1-weighted and hyperintense signal intensity on T2-weighted imaging sequences. The underlying kidneys may show reversal of corticomedullary signal with hypointense medulla and hyperintense cortex. MRI has better soft-tissue contrast resolution, enhancing depiction of smaller cysts around the renal pelvis, and is preferable in the presence of decreased kidney function.5,11,13,14 The differential diagnosis of multiple perinephric cystic lesions of renal lymphangiectasia on imaging is associated with acquired renal cystic disease, hereditary (autosomal dominant) polycystic kidneys, and rarely, cystic renal tumors and nephroblastomatosis.3,4 Identification of an extracortical location with normal parenchyma and homogenous fluid signal/ attenuation of the cysts gives a clue to the diagno350
sis.3,4,5,12 An advanced stage of renal lymphangiectasia when multiple cystic or multiseptate appearance is replaced with an isolated large perinephric fluid collection needs to be differentiated from other causes of perinephric fluid, including hematoma, abscess, urinoma, and nephropathy with floating kidneys.1,4 Abscess can be diagnosed when peripheral enhancement is seen around the fluid collection with septic features. Hematoma can be identified from hyperintense signal on T1-weighted images in the presence of a relevant history of trauma. Urinoma can be identified on computed tomographic urography when excreted contrast escapes into the collection. An aspirate would show a high creatinine concentration in the case of urinoma.1,4,8 Normal kidney function, typical simple fluid appearance, classic findings in contralateral kidney, and retroperitoneal fluid collection around the aorta and inferior vena cava helped make the diagnosis of renal lymphangiectasia in our patient. Difficult cases may be confirmed by aspiration of fluid to distinguish urinoma and abscess, and a renal origin of lymphangiectasia can be identified from a high renin level.12 Renal lymphangiectasia has benign behavior and is asymptomatic, and this demands conservative management. However, it may progress rapidly, as in pregnancy, or may be complicated by decreased kidney function. Symptomatic collections can be drained percutaneously to relieve compression.7,9 Hypertension and ascites can be treated using diuretics and antihypertensive medication. Recurrent collections demanding treatment can be marsupialized into the peritoneum. Nephrectomy is reserved for recurring complicated collections and may be needed in patients with uncontrolled intraoperative bleeding.4,7,12 Asymptomatic patients may be followed up to recognize a change in kidney function early.11,12 In summary, renal lymphangiectasia is a benign condition involving the kidneys that can be diagnosed from the characteristic imaging appearance of perinephric cysts and fluid collections with normal renal cortex. Imaging allows noninvasive differentiation of this condition from cystic, neoplastic, and other pathologic states of kidneys that require some sort of intervention.
ACKNOWLEDGEMENTS Support: None. Financial Disclosure: The authors declare that they have no relevant financial interests.
REFERENCES 1. Wani NA, Mir F, Gojwari T, Qureshi UA, Ahmad R. Subcapsular fluid collection: an unusual manifestation of nephrotic syndrome. Am J Kidney Dis. 2010;56(1):181-184. Am J Kidney Dis. 2011;57(2):347-351
Renal Lymphangiectasia 2. Meredith WT, Levine E, Ahlstrom NG, Grantham JJ. Exacerbation of familial renal lymphangiomatosis during pregnancy. AJR Am J Roentgenol. 1988;151(5):965-966. 3. Ramseyer LT. Case 34: renal lymphangiectasia. Radiology. 2001;219(2):442-444. 4. Ashraf K, Raza SS, Ashraf O, Memon W, Memon A, Zubairi TA. Renal lymphangiectasia. Br J Radiol. 2007;80(954):e117-118. 5. Gupta R, Sharma R, Gamanagatti S, Dogra PN, Kumar A. Unilateral renal lymphangiectasia: imaging appearance on sonography, CT and MRI. Int Urol Nephrol. 2007; 39(2):361-364. 6. Kim JK, Ahn HJ, Kim KR, Cho KS. Renal lymphangioma manifested as a solid mass on ultrasonography and computed tomography. J Ultrasound Med. 2002;21(2):203-206. 7. Riehl J, Schmitt H, Schäfer L, Schneider B, Sieberth G. Retroperitoneal lymphangiectasia associated with bilateral renal vein thrombosis. Nephrol Dial Transplant. 1997;12(8):1701-1703. 8. Sarikaya B, Akturk Y, Bekar U, Topaloglu S. Bilateral renal lymphangiomatosis mimicking hydronephrosis: multidetector CT urographic findings. Abdom Imaging. 2006;31(6):732-734.
Am J Kidney Dis. 2011;57(2):347-351
9. Ozmen M, Deren O, Akata D, Akhan O, Ozen H, Durukan T. Renal lymphangiomatosis during pregnancy: management with percutaneous drainage. Eur Radiol. 2001;11(1):37-40. 10. Varela JR, Bargiela A, Requejo I, Fernandez R, Darriba M, Pombo F. Bilateral renal lymphangiomatosis: US and CT findings. Eur Radiol. 1998;8(2):230-231. 11. Llorente JG, García AD, Sacristan JS, Chicharro GN. Renal lymphangiectasia: radiologic diagnosis and evolution. Abdom Imaging. 2002;27(6):637-679. 12. Rastogi R, Rastogi V. Computed tomographic scan in the diagnosis of bilateral renal lymphangiectasia. Saudi J Kidney Dis Transpl. 2008;19(6):976-979. 13. Kocaoglu M, Bulakbasi N, Ilica T, Somuncu I. MRI findings of renal lymphangiectasia. J Magn Reson Imaging. 2005;22(5): 681-683. 14. Upreti L, Dev A, Kumar Puri S. Imaging in renal lymphangiectasia: report of two cases and review of literature. Clin Radiol. 2008; 63(9):1057-1062.
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INTRODUCTION Fluid collections may form around the kidneys in various pathologic conditions. Imaging using ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) may help identify the fluid and localizes the collection with respect to subcapsular, perirenal, or pararenal spaces. A combination of clinical features in conjunction with radiologic findings on cross-sectional imaging helps determine the nature of fluid collection, including urinoma, hematoma, or abscess.1 Postoperative lymphocele/ fluid collections may form around the kidneys after transplant. Sometimes lymphatic fluid may collect in the form of lymphangiomas in various parts of the body caused by defective development and communication of lymphatics. Renal involvement by this lymphatic space dilatation, called lymphangiectasia, may result in peripelvic renal cyst formation and/or fluid collections around the kidneys.2
CASE REPORT Clinical History and Initial Laboratory Data A 60-year-old man presented with concerns of breathlessness and fatigue for the last month. Other than smoking, he had no relevant medical history. On examination, he was pale, pulse was 90 beats/min, and blood pressure was 130/86 mm Hg. Heart and lungs were normal, and lymphadenopathy was absent. On abdominal examination, soft ballotable swelling was palpable in the right lumbar region and right renal angle. Mild splenomegaly was present. Routine blood investigations showed the following values: hemoglobin, 8 g/dL (80 g/L) with microcytic hypochromic picture; total leukocyte count, 8 ⫻103/L (8 ⫻109/L); and platelet count, 350 ⫻103/L (350 ⫻109/L). Urinalysis had normal results, with no significant proteinuria, red blood cells, or casts in urine. Serum chemistry tests showed the following values: sodium, 140 mEq/L (140 mmol/L); potassium, 4.2 mEq/L (4.2 mmol/L); calAm J Kidney Dis. 2011;57(2):347-351
cium, chloride, and bicarbonate also were within the reference ranges; serum urea nitrogen, 31 mg/dL (11.06 mmol/L); and serum creatinine, 1.1 mg/dL (97.24 mol/L), with estimated glomerular filtration rate of 73 mL/min/1.73 m2 (1.22 mL/s/1.73 m2). Serum albumin, total cholesterol, blood glucose (fasting), and liver function test results were unremarkable. Serum iron and ferritin levels were low, and total iron-binding capacity and erythropoietin level were increased. Stool examination for occult blood was negative. Upper- and lower-gastrointestinal endoscopic examinations did not show a pathologic state.
Imaging Studies Transabdominal US with a curvilinear transducer showed a large anechoic fluid collection without septations around the right kidney, displacing the kidney anteriorly. The right kidney appeared bright in echotexture because of through transmission from the surrounding fluid; size and corticomedullary differentiation were normal. No hydronephrosis, calculus, or cyst was seen in the kidney. The left kidney was surrounded by multiple variable-sized anechoic fluid collections with intervening septations without debris (Fig 1). The underlying kidney was normal in size and corticomedullary differentiation without hydronephrosis or mass lesion. There was no free fluid in the peritoneal cavity. CT was performed using multidetector-row CT after intravenous injection of iodinated contrast, which showed a large homogenous hypodense (0-10 HU [Hounsfield units]) fluid collection around the bilateral kidneys predominant on the posterior aspects. Fluid
From the Departments of 1Radiodiagnosis and Imaging and Pediatrics, Sher-I-Kashmir Institute of Medical Sciences, Srinagar, India. Received April 9, 2010. Accepted in revised form June 30, 2010. Originally published online October 1, 2010. Address correspondence to Nisar A. Wani, MD, Department of Radiodiagnosis and Imaging, Sher-I-Kashmir Institute of Medical Sciences (SKIMS), Srinagar 190011, India. E-mail: ahmad77chinar@ hotmail.com © 2011 by the National Kidney Foundation, Inc. 0272-6386/$36.00 doi:10.1053/j.ajkd.2010.06.028
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Wani et al
Figure 1. Ultrasound image of the kidneys shows a large anechoic collection displacing and compressing the right kidney (rightward arrow); the left kidney is surrounded by multiseptate anechoic fluid collection (leftward arrow). The renal cortex of the kidneys is separate and away from the cyst and fluid collection and shows a bright echopattern due to through transmission via the surrounding fluid.
collection was larger around the right kidney, displacing it anteriorly; no septations were seen in the perirenal collections. A thin fluid collection was visualized around the aorta and inferior vena cava in the midline retroperitoneum; no intrarenal cyst, collection, or hydronephrosis was seen; and sinus fat was prominent (Fig 2A). Both kidneys showed normal excretion of contrast into the nondilated pelvicaliceal system, which did not communicate with the perinephric fluid (Fig 2B). MRI showed the perirenal fluid collection as homogenously hypointense on T1-weighted and hyperintense on T2-weighted sequences, suggesting simple fluid. No septations were seen in the right perirenal collection, whereas the left-sided collection was composed of multiple thin-walled cysts of variable size separate from the renal cortex. Kidneys appeared normal in size, and signal intensity without intraparenchymal cysts or hydronephrosis (Fig 3A and B).
Diagnosis Perinephric fluid collections due to renal lymphangiectasia.
Clinical Follow-up The patient was started on oral iron therapy for the symptomatic iron deficiency anemia. US-guided aspiration of the fluid was performed for cytologic evaluation, which showed a leukocyte count of 40 cells/L with predominant (90%) lymphocytes and protein level of
0.6 g/dL (6 g/L). No bacteria could be stained or cultured from the aspirate. The patient was advised to undergo serial kidney function tests and imaging follow-up.
DISCUSSION Renal lymphangiectasia is a benign disease of renal lymphatics, also known as renal lymphangiomatosis, renal lymphangiomas, peripelvic lymphangiectasia, and renal peripelvic multicystic lymphangiectasia. Because this disorder is characterized by ectasia of the peripelvic, perirenal, and intrarenal lymphatic vessels, the term renal lymphangiectasia is preferred.3 Abnormal dilatation of these lymphatic ducts arises from their failure of communication with larger retroperitoneal lymph vessels. This may be a congenital abnormality or a gradually progressive acquired dysfunction of lymphatics. Although usually bilateral, renal lymphangiectasia may be unilateral or focal.4 Dilated lymphatics more commonly may appear inside kidneys in the peripelvic area, resulting in intrarenal
Figure 2. (A) Transverse computed tomographic image in the nephrographic phase shows a perirenal fluid attenuation collection posterior to the right kidney, displacing it anteriorly (left upward arrow); a smaller collection is seen around the left kidney, which is in place (right upward arrow). Thinner fluid attenuation is seen in the midline around the aorta and inferior vena cava in the retroperitoneum (downward arrow). The renal cortex is separate from the fluid. (B) Coronal reformat computed tomography in the excretory phase shows bilateral perirenal fluid attenuation with normal underlying renal parenchyma (upward arrows). The pelvicaliceal system outlined by the excreted contrast is not dilated and sinus fat is prominent in both kidneys (downward arrows). 348
Am J Kidney Dis. 2011;57(2):347-351
Renal Lymphangiectasia
Figure 3. (A) T2-weighted axial magnetic resonance image shows a homogenous hyperintense signal intensity perirenal collection around the right kidney, posteriorly displacing it (downward arrow); the left kidney is surrounded by multiple variable-sized similar hyperintense signal intensity cysts posteriorly and laterally (upward arrow). The renal cortex is well separated from the cysts and fluid collection and shows normal signal intensity. (B) Coronal T2-weighted magnetic resonance image shows perirenal homogenous hyperintense (fluid) signal intensity in the form of multiple cysts around the left kidney (leftward arrow) and a larger collection around the right kidney (downward arrow). Kidneys appear normal in size.
lymphangiectasia, or less commonly in the perinephric tissue, resulting in extrarenal lymphangiectasia.5 Usually seen in children, isolated or predominant involvement of small renal parenchymal lymphatics may result in bilateral nephromegaly. Thin small fluid collections may form in the midline retroperitoneum around the aorta and inferior vena cava.5,6 Dilatation of larger peripelvic lymph channels results in peripelvic cysts, seen in the general population. Another name for peripelvic cysts is intrarenal lymphangiectasia. Peripelvic cysts are easy to detect by means of US and CT because of their position in the renal sinus.7 Although their flat fanlike shape may distinguish them from the more common cortical cysts, they may
be confused with hydronephrosis (Fig 4A).7 The lack of communication between the individual cystic components and the pelvicaliceal system in the excretory phase of contrast-enhanced CT and MRI suggests the diagnosis of intrarenal lymphangiectasia (Fig 4B). The complete picture of renal lymphangiectasia resulting in a combination of peripelvic cysts and perinephric cysts is an unusual entity that has a characteristic appearance on imaging.3 Renal lymphangiectasia may present at any age, with equal involvement in men and women. Patients may present with abdominal distension, flank pain, or abdominal lump. It also may present as an incidental finding in patients with unrelated symptoms. Hyperten-
Figure 4. (A) Ultrasound image of a kidney shows multiple noncommunicating anechoic lesions representing peripelvic cysts (arrows) in a case of intrarenal lymphangiectasia; hydronephrosis is a close differential diagnosis. (B) Contrast-enhanced transverseplane computed tomographic image in the excretory phase shows fluid attenuation areas (arrows) around the contrast-outlined pelvicaliceal system in a case of intrarenal lymphangiectasia with more prominent peripelvic cysts in the left kidney. Am J Kidney Dis. 2011;57(2):347-351
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Wani et al
sion, hematuria, proteinuria, renal vein thrombosis, and ureteric obstruction have been reported in patients with renal lymphangiectasia.7,8 Extrinsic compression of the kidneys may alter kidney function or result in Page kidney. Perirenal lymphangiomas may be complicated by hemorrhage. Marked expansion of the perirenal fluid collection and development of ascites may be exacerbated by pregnancy.2,9 Before the advent of modern cross-sectional imaging modalities, the diagnosis of renal lymphangiectasia was made after exploratory laparotomy or nephrectomy. Although intravenous pyelography may show distortion of the pelvicaliceal system by the intrapelvic or perinephric cysts, this finding is nonspecific. Findings of US, CT, and MRI are characteristic of renal lymphangiectasia.5,10-14 Noninvasive diagnosis can be accomplished in most cases using US, with CT required in some cases. US shows the dilated lymphatic vessel as anechoic multiseptate thin-walled fluid collections (cysts) with posterior acoustic enhancement in the peripelvic and perirenal locations. Sometimes larger fluid collections without septations may form around the kidney, compressing and displacing it. Kidneys may be normal sized or enlarged, and renal echogenicity may be increased with the corticomedullary differentiation altered.5,6,10 Renal lymphangiectasia on CT is seen as nonenhancing hypodense attenuation (0-10 HU) collections around bilateral kidneys and in the peripelvic region. Intervening septations may or may not be visualized. CT enhances the demonstration of pelvic, peripelvic, and perirenal cysts and their relationship with the renal vessels and parenchyma, and computed tomographic urography allows delineation of the pelvicaliceal system. Associated smaller and thinner fluid collections around the aorta and inferior vena cava in the retroperitoneum are shown better using CT.5,6,8,10-12 MRI confirms the fluid nature in peripelvic and perirenal cysts and collections from the homogenous hypointense signal intensity on T1-weighted and hyperintense signal intensity on T2-weighted imaging sequences. The underlying kidneys may show reversal of corticomedullary signal with hypointense medulla and hyperintense cortex. MRI has better soft-tissue contrast resolution, enhancing depiction of smaller cysts around the renal pelvis, and is preferable in the presence of decreased kidney function.5,11,13,14 The differential diagnosis of multiple perinephric cystic lesions of renal lymphangiectasia on imaging is associated with acquired renal cystic disease, hereditary (autosomal dominant) polycystic kidneys, and rarely, cystic renal tumors and nephroblastomatosis.3,4 Identification of an extracortical location with normal parenchyma and homogenous fluid signal/ attenuation of the cysts gives a clue to the diagno350
sis.3,4,5,12 An advanced stage of renal lymphangiectasia when multiple cystic or multiseptate appearance is replaced with an isolated large perinephric fluid collection needs to be differentiated from other causes of perinephric fluid, including hematoma, abscess, urinoma, and nephropathy with floating kidneys.1,4 Abscess can be diagnosed when peripheral enhancement is seen around the fluid collection with septic features. Hematoma can be identified from hyperintense signal on T1-weighted images in the presence of a relevant history of trauma. Urinoma can be identified on computed tomographic urography when excreted contrast escapes into the collection. An aspirate would show a high creatinine concentration in the case of urinoma.1,4,8 Normal kidney function, typical simple fluid appearance, classic findings in contralateral kidney, and retroperitoneal fluid collection around the aorta and inferior vena cava helped make the diagnosis of renal lymphangiectasia in our patient. Difficult cases may be confirmed by aspiration of fluid to distinguish urinoma and abscess, and a renal origin of lymphangiectasia can be identified from a high renin level.12 Renal lymphangiectasia has benign behavior and is asymptomatic, and this demands conservative management. However, it may progress rapidly, as in pregnancy, or may be complicated by decreased kidney function. Symptomatic collections can be drained percutaneously to relieve compression.7,9 Hypertension and ascites can be treated using diuretics and antihypertensive medication. Recurrent collections demanding treatment can be marsupialized into the peritoneum. Nephrectomy is reserved for recurring complicated collections and may be needed in patients with uncontrolled intraoperative bleeding.4,7,12 Asymptomatic patients may be followed up to recognize a change in kidney function early.11,12 In summary, renal lymphangiectasia is a benign condition involving the kidneys that can be diagnosed from the characteristic imaging appearance of perinephric cysts and fluid collections with normal renal cortex. Imaging allows noninvasive differentiation of this condition from cystic, neoplastic, and other pathologic states of kidneys that require some sort of intervention.
ACKNOWLEDGEMENTS Support: None. Financial Disclosure: The authors declare that they have no relevant financial interests.
REFERENCES 1. Wani NA, Mir F, Gojwari T, Qureshi UA, Ahmad R. Subcapsular fluid collection: an unusual manifestation of nephrotic syndrome. Am J Kidney Dis. 2010;56(1):181-184. Am J Kidney Dis. 2011;57(2):347-351
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