1. Large abdominal Cystic masses in childhood: diagnostic imaging. AB Valentín Martín P Calvo Azabarte MC Villaespesa MJ Adán Martín MJ Adán Martín A Pérez Martínez A Pérez Martínez C Caracela Zeballos Servicio de Radiodiagnóstico Hospital Virgen de la Salud, Toledo (ESPAÑA/ SPAIN)

2. Learning Objectives: To review the radiologic findings of cystic abdominal masses in childhood, showing those imaging features that facilitate differential diagnosis. To review the radiologic findings of cystic abdominal masses in childhood, showing those imaging features that facilitate differential diagnosis.

3. Background: In childhood, abdominal cystic masses have multiple etiologies. In childhood, abdominal cystic masses have multiple etiologies. In this exhibit, we will review the large abdominal cystic masses diagnosed in our hospital, based on a series of 32 children under 14 year-old with masses originating in the urogenital system, gastrointestinal and hepatobiliary tract, peritoneum and retroperitoneum. In this exhibit, we will review the large abdominal cystic masses diagnosed in our hospital, based on a series of 32 children under 14 year-old with masses originating in the urogenital system, gastrointestinal and hepatobiliary tract, peritoneum and retroperitoneum.

4. We will analyze the characteristic imaging findings on plain films, ultrasound (US), computed tomographic (CT) and magnetic resonance (MR). We will analyze the characteristic imaging findings on plain films, ultrasound (US), computed tomographic (CT) and magnetic resonance (MR).

5. Because the large abdominal cystic masses distort normal anatomy, their site of origin can be difficult to ascertain. Because the large abdominal cystic masses distort normal anatomy, their site of origin can be difficult to ascertain. Information regarding size, location, epicenter of the mass, sites of attachment and tissue characteristics in conjunction with the patient's age and the clinical history, will allow the radiologist to offer likely differential diagnostic possibilities. Information regarding size, location, epicenter of the mass, sites of attachment and tissue characteristics in conjunction with the patient's age and the clinical history, will allow the radiologist to offer likely differential diagnostic possibilities.

6. Imaging Findings: Abdominal cystic masses that we will review are: Abdominal cystic masses that we will review are: -UROGENITAL SYSTEM: hydronephrosis, multicystic kidney, urachal cyst, cystic ovarian masses. -GASTROINTESTINAL TRACT: enteric cyst, volvulus, appendiceal abscess, Meckel's diverticulum and intussusception. -HEPATOBILIARY TRACT: hepatic cysts and choledochal cysts -OTHER: pancreatic pseudocyst, splenic cyst, lymphatic malformation, cystic neuroblastoma, Wilms tumor and pseudocyst due to ventriculo-peritoneal derivation. We present various cases of these lesions, reviewing radio-pathological features and differential diagnosis. We present various cases of these lesions, reviewing radio-pathological features and differential diagnosis.

7. UROGENITAL SYSTEM: 1. Hydronephrosis Distension and dilation of the renal pelvis and calyces, usually caused by obstruction of the free flow of urine from the kidney, leading to progressive atrophy of the kidney Distension and dilation of the renal pelvis and calyces, usually caused by obstruction of the free flow of urine from the kidney, leading to progressive atrophy of the kidney Distensiondilationrenal pelviscalycesobstructionurinekidneyatrophy Distensiondilationrenal pelviscalycesobstructionurinekidneyatrophy Hydronephrosis = dilatation of the upper urinary tracts ≠ obstruction. Hydronephrosis = dilatation of the upper urinary tracts ≠ obstruction. Caliceal dilatation = always abnormal Caliceal dilatation = always abnormal It is the most common abdominal mass in neonates. It is the most common abdominal mass in neonates. Causes: Causes: Ureteropelvic junction obstruction, Ureteropelvic junction obstruction, Vesico-ureteral reflux Vesico-ureteral reflux Less frequently: Less frequently: Ureterovesical junction obstruction Ureterovesical junction obstruction Duplication anomalies, ureterocoeles and ectopic ureters Duplication anomalies, ureterocoeles and ectopic ureters Posterior urethral valves Posterior urethral valves

8. Ultrasound Findings (hydronephrosis by ureteropelvic junction obstruction,): Right kidney: normal characteristics. -Left kidney: enlarged, with multiple cystic structures of uniform size (very dilated calyces) that communicate among themselves and with other central cystic structure (also very dilated pelvis). The ureter isn´t dilatated. Loss of cortical (more or less, depending on time of evolution) Ultrasound Findings (hydronephrosis by ureteropelvic junction obstruction,): -Right kidney: normal characteristics. -Left kidney: enlarged, with multiple cystic structures of uniform size (very dilated calyces) that communicate among themselves and with other central cystic structure (also very dilated pelvis). The ureter isn´t dilatated. Loss of cortical (more or less, depending on time of evolution)

9. UROGENITAL SYSTEM: 2- Urologic congenital malformations A 1-month old male. US: Normal right kidney (RK). Absence of left kidney. Blind distal ureter, dilated and tortuous (yellow arrow). MRI: the findings* are confirmed Coronal T2-weighted MR image Coronal post-gadolinium T1-weighted MR image RK

10. UROGENITAL SYSTEM: 3. Urachal cyst A 6 year-old girl. with nonspecific abdominal discomfort.. US: Urachal cyst Urachus: a midline tubular structure that extends upward from the anterior dome of the bladder toward the umbilicus. Urachus: a midline tubular structure that extends upward from the anterior dome of the bladder toward the umbilicus. It normally involutes before birth, remaining as a fibrous band. However, persistence of an embryonic urachal remnant can give rise to various clinical problems. It normally involutes before birth, remaining as a fibrous band. However, persistence of an embryonic urachal remnant can give rise to various clinical problems. Congenital urachal anomalies: Congenital urachal anomalies: 1. Patent urachus(50%) 2. Umbilical-urachal sinus (15%) 3. Vesicourachal diverticulum (3-5%) 4. Urachal cyst. (30%) Location: lower one-third of the urachus Location: lower one-third of the urachus usually small. (but they can become large) usually small. (but they can become large) US shows a fluid-filled cavity in the midline lower abdominal wall. US shows a fluid-filled cavity in the midline lower abdominal wall. Infection is the most common complication Infection is the most common complication US: a thick-walled cystic mass with mixed echogenicity above the bladder. US: a thick-walled cystic mass with mixed echogenicity above the bladder. CT: a thick-walled cystic lesion with perilesional infiltration. CT: a thick-walled cystic lesion with perilesional infiltration.

11. UROGENITAL SYSTEM: 4. Ovarian Cysts Ovarian cyst is an uncommon cause of an abdominal mass in the newborn. Ovarian cyst is an uncommon cause of an abdominal mass in the newborn. Under the influence of the maternal hormones, simple ovarian cysts may form in neonates. Under the influence of the maternal hormones, simple ovarian cysts may form in neonates. US: US: well-defined unilocular cysts well-defined unilocular cysts Content anechoic with posterior acoustic enhancement. Content anechoic with posterior acoustic enhancement. with an imperceptible wall with an imperceptible wall Doppler flow studies: absence of any blood flow within cysts Doppler flow studies: absence of any blood flow within cystsEvolution:  resolution (if diameter <4cm)  complication: torsion hemorrhage break Simple ovarian cysts 2 months old girl. Normal ovaries. Transverse US Sagital US Color Doppler imaging

12. US: Twisted ovary: Twisted ovary: Enlarged Ovary Enlarged Ovary Free fluid Free fluid Complex cystic mass Complex cystic mass Color Doppler: avascular twisted ovary Color Doppler: avascular twisted ovary Hemorrhagic ovarian cyst: Hemorrhagic ovarian cyst: Heterogeneous mass (ultrasound presentation varies according to the time course of blood. -fresh blood: anechoica -subacute: heterogeneous (on going been producing the contraction of the clot and thrombus) -finally: anecogénico (with clot lysis) Heterogeneous mass (ultrasound presentation varies according to the time course of blood. -fresh blood: anechoica -subacute: heterogeneous (on going been producing the contraction of the clot and thrombus) -finally: anecogénico (with clot lysis) Thick wall Thick wall Septations Septations Fluid-debris levels Fluid-debris levels Twisted ovary Hemorrhagic ovarian cyst

13. Duplications of the alimentary tract are spherical or tubular structures lined by epithelium similar to intestine that are firmly attached to or share the wall of the alimentary tract and have a common blood supply with the adjacent segment of the bowel. Duplications of the alimentary tract are spherical or tubular structures lined by epithelium similar to intestine that are firmly attached to or share the wall of the alimentary tract and have a common blood supply with the adjacent segment of the bowel. Completely isolated duplication cysts are an extremely rare variety of gastrointestinal duplications. Completely isolated duplication cysts are an extremely rare variety of gastrointestinal duplications. GASTROINTESTINAL 1-Gastrointestinal duplication cyst

14. Etiology: congenital Etiology: congenital Location: Anywhere along the digestive tract. Location: Anywhere along the digestive tract. Most often associated with the esophagus (18%) and jejunum/ileum (53%) Most often associated with the esophagus (18%) and jejunum/ileum (53%) General features: General features: Cystic lesion with a well-defined wall. Cystic lesion with a well-defined wall. Bowell wall signature on US: echogenic mucosa, hypoechoic muscular layer and echogenic serosa. Bowell wall signature on US: echogenic mucosa, hypoechoic muscular layer and echogenic serosa. They are usually attached to the bowel wall (usually the muscle layer is shared with the adjacent bowel wall) They are usually attached to the bowel wall (usually the muscle layer is shared with the adjacent bowel wall)

15. US: a tubular or spherical cystic mass, sometimes with internal echoes (blood, debris). They are usually solitary. They have a well defined wall with characteristic bowell wall signature: an inner echogenic rim (1-2mm thick) of intestinal mucosa surrounded by a characteristic hypoechoic rim (1-2mm thick) of muscle in the wall. Water intake: cyst excluded - If they're big: floating masses or mimic ascites -Septa and calcification rare. US with water in bowell.Cyst excluded. Normal gallbladder and bile duct

16. HEPATOBILIARY TRACT 1. Choledochal cysts Choledochal cysts are congenital anomalies of the bile ducts. They consist of cystic dilatations of the extrahepatic biliary tree, intrahepatic biliary radicles, or both (without involvement of the gallbladder or cystic duct). Choledochal cysts are congenital anomalies of the bile ducts. They consist of cystic dilatations of the extrahepatic biliary tree, intrahepatic biliary radicles, or both (without involvement of the gallbladder or cystic duct). Diagnosis: Most patients present in the first decade of life. 30% are diagnosed in the first year of life 50% between 1-10 year-old. 20% in the second decade Diagnosis: Most patients present in the first decade of life. 30% are diagnosed in the first year of life 50% between 1-10 year-old. 20% in the second decade Classic triad of symptoms : right upper quadrant mass + pain + jaundice If it breaks: bilious ascites Classic triad of symptoms : right upper quadrant mass + pain + jaundice If it breaks: bilious ascites

17. Types They were classified into 5 types by Todani in 1977. Classification was based on site of the cyst or dilatation. : Most common variety (80-90%) involving sacular or fusiform dilatation of a portion or entire common bile duct (CBD) with normal intrahepatic duct. Type I cysts can be divided into 3 subclassifications, including type IA cysts, which are typically saccular and involve all or a major portion of the extrahepatic bile duct (common hepatic duct plus common bile duct) Type I: Most common variety (80-90%) involving sacular or fusiform dilatation of a portion or entire common bile duct (CBD) with normal intrahepatic duct. Type I cysts can be divided into 3 subclassifications, including type IA cysts, which are typically saccular and involve all or a major portion of the extrahepatic bile duct (common hepatic duct plus common bile duct)common bile ductcommon bile duct Type II or choledochal cysts: (2%) Isolated diverticulum protruding from the CBD. Type III or Choledochocele: Arise from dilatation of duodenal portion of CBD or where pancreatic duct meets. Type IV: Dilatation of both intrahepatic and extrahepatic biliary duct. Type IVA cysts - These are characterized by multiple dilatations of the intrahepatic and extrahepatic biliary tree. Most frequently, a large, solitary cyst of the extrahepatic duct is accompanied by multiple cysts of the intrahepatic ducts. Type IVA cysts - These are characterized by multiple dilatations of the intrahepatic and extrahepatic biliary tree. Most frequently, a large, solitary cyst of the extrahepatic duct is accompanied by multiple cysts of the intrahepatic ducts. Type IVB choledochal cysts - These consist of multiple dilatations that involve only the extrahepatic bile duct. Type IVB choledochal cysts - These consist of multiple dilatations that involve only the extrahepatic bile duct. Type V or Caroli's disease: Cystic dilatation of intra hepatic biliary ducts

18. US: US: A right upper quadrant cystic or fusiform mass with in the porta hepatis, separate from the gallbladder, with bile duct(s) leading into or out of it, is diagnostic of a choledochal cyst. Its relationship to the pancreas and intrahepatic biliary tree should also be ascertained. A right upper quadrant cystic or fusiform mass with biliary sludge in the porta hepatis, separate from the gallbladder, with bile duct(s) leading into or out of it, is diagnostic of a choledochal cyst. Its relationship to the pancreas and intrahepatic biliary tree should also be ascertained.

19. Projective MR images showing marked saccular dilation of the common bile duct. T2- weighted MPR Coronal T1-weighted MR image

20. ymphatic malformation OTHER: 1. L ymphatic malformation A 3-year-old girl with a 1-week history of constipation and abdominal pain. Abdominal radiograph shows a paucity of bowel gas in the right side of the abdomen US: a multisepta cystic mass, located at infrahepatic. The lesion measured 12cm craniocaudally. Mesenteric lymphadenopathy.

21. Coronal contrast-enhanced CT CT with IV contrast: A hypodense multicystic mass, well- defined, with thin walls, located in the right iliac fossa, anterior to the iliac vessels. CT confirms that the cyst is not arising from another organ such as the kidney, pancreas, or ovary. Laparotomy : Lymphatic malformation in jejunum. Resection with primary anastomosis Sagital contrast-enhanced CT Coronal contrast-enhanced CT Lymphatic malformation in jejunum.

22. Most cystic lymphatic malformations are found in the head or neck. Most cystic lymphatic malformations are found in the head or neck. Intra-abdominal locations such as omentum, mesentery, and retroperitoneum are unusual. Intra-abdominal locations such as omentum, mesentery, and retroperitoneum are unusual. A lack of communication between small bowel or retroperitoneal tissue and the main lymphatic vessels forms a mass that can develop into mesenteric and omental lymphatic cysts. A lack of communication between small bowel or retroperitoneal tissue and the main lymphatic vessels forms a mass that can develop into mesenteric and omental lymphatic cysts. Commonly found in the ileal mesentery, they can also occur from the duodenum to the rectum. Commonly found in the ileal mesentery, they can also occur from the duodenum to the rectum.

23. These cysts can be simple or multiple, unilocular or multilocular. These cysts can be simple or multiple, unilocular or multilocular. They may contain hemorrhagic, serous, chylous, or infected fluid. They may contain hemorrhagic, serous, chylous, or infected fluid. Calcifications are rare. Calcifications are rare. They can range in size from a few millimeters to 40 cm in diameter. Often they are larger than those of enteric duplication. They can range in size from a few millimeters to 40 cm in diameter. Often they are larger than those of enteric duplication. Based on the size of the lymphatic spaces within the malformation, cystic lymphatic malformations can be divided into microcystic lesions and macrocystic lesions: Based on the size of the lymphatic spaces within the malformation, cystic lymphatic malformations can be divided into microcystic lesions and macrocystic lesions: ----solitary cyst mesenteric / omentum ----multilocular cyst ----diffuse abdominal lymphangiomatosis ----solitary cyst mesenteric / omentum ----multilocular cyst ----diffuse abdominal lymphangiomatosis

24. Total resection is the treatment of choice. When the cyst adheres to the intestinal wall and mesentery, resection of the adjacent intestine may be necessary. Extensive lesions that adhere to vascular mesenteric elements may require partial resection. Total resection is the treatment of choice. When the cyst adheres to the intestinal wall and mesentery, resection of the adjacent intestine may be necessary. Extensive lesions that adhere to vascular mesenteric elements may require partial resection.

25. OTHER: Cystic neuroblastoma: OTHER: 2. Cystic neuroblastoma: Neuroblastoma is a lesion of the sympathetic nerve chain and may arise anywhere along the axis of these sympathetic nerves. Neuroblastoma is a lesion of the sympathetic nerve chain and may arise anywhere along the axis of these sympathetic nerves. About 66% of these tumors arise in the abdomen and appear most frequently in the adrenal gland – the suprarenal region. About 66% of these tumors arise in the abdomen and appear most frequently in the adrenal gland – the suprarenal region. Second most common abdominal tumor in childhood. Second most common abdominal tumor in childhood. The majority of cases of neuroblastoma occur in children aged 6 months to 5 years. The majority of cases of neuroblastoma occur in children aged 6 months to 5 years.

26. Cystic neuroblastoma is a rare form of neuroblastoma. Hemorrhage and necrosis are often seen in neuroblastoma, but cyst formation is uncommon. Cystic neuroblastoma is a rare form of neuroblastoma. Hemorrhage and necrosis are often seen in neuroblastoma, but cyst formation is uncommon. It moves and compresses the kidney. It moves and compresses the kidney. It is a poorly defined and heterogeneous tumor with calcification. It is a poorly defined and heterogeneous tumor with calcification.

27. The possible routes of spread are: The possible routes of spread are: Local Local Lymph nodes and extensive nodal masses Lymph nodes and extensive nodal masses Invasion of neural foramina, causing deviation of dural sac Invasion of neural foramina, causing deviation of dural sac Encasement of great vessels (unlike nephroblastoma). Encasement of great vessels (unlike nephroblastoma). ● Remote (hematogenous) ● Remote (hematogenous) Bone Bone Liver Liver Central nervous system: extradural space and orbit region Central nervous system: extradural space and orbit region

28. Imaging findings: The plain film findings frequently show stippled calcification, with lateral and downward displacement of the kidney. The plain film findings frequently show stippled calcification, with lateral and downward displacement of the kidney. US: an echogenic or complex extrarenal mass compressing or displacing the kidney inferiorly and laterally. They have a variable echogenicity with irregular hyperechoic areas intermixed with less echogenic areas, apparently corresponding to the frequent foci of hemorrhage, necrosis, and microcalcification in these tumors. Large focal calcifications may produce very intense echoes and occasional shadowing. US: an echogenic or complex extrarenal mass compressing or displacing the kidney inferiorly and laterally. They have a variable echogenicity with irregular hyperechoic areas intermixed with less echogenic areas, apparently corresponding to the frequent foci of hemorrhage, necrosis, and microcalcification in these tumors. Large focal calcifications may produce very intense echoes and occasional shadowing. Cross-sectional imaging with CT and MR helps to define the extent of the primary tumor and to detect metastases. Cross-sectional imaging with CT and MR helps to define the extent of the primary tumor and to detect metastases.

29. Cystic neuroblastoma Cystic neuroblastoma 2-day-old girl with a palpable abdominal mass. US: A cystic mass in right adrenal area, with multiple septa within. Axial T2-weighted image : a hyperintense and heterogeneous. adrenal mass. Axial post-gadolinium T1- weighted MR image : no enhancement. CoronalT2-weighted image :CoronalT2-weighted image : a hyperintense mass in right adrenal area, which mark the upper pole of the kidney. Gross specimen. Reddish-brown cyst formation in the unrecognized adrenal gland normal. US Axial T2-weighted image Axial post-gadolinium T1-weighted MR image CoronalT2-weighted image

30. 3. Wilms Tumor 4-month-old boy with an asintomatic abdominal flank mass. US Abdominal radiograph Coronal contrast-enhanced CT Axial contrast-enhanced CT

31. Wilms tumor is the most common primary malignant renal tumor in children, accounting for 7% of all childhood cancers. Wilms tumor is the most common primary malignant renal tumor in children, accounting for 7% of all childhood cancers. The mean age at diagnosis is 3.5 years. The mean age at diagnosis is 3.5 years. The third cause of renal mass in childhood after hydronephrosis and multicystic renal dysplasia. The third cause of renal mass in childhood after hydronephrosis and multicystic renal dysplasia. Most nephroblastomas are unilateral, being bilateral in less than 5% of cases. Most nephroblastomas are unilateral, being bilateral in less than 5% of cases.

32. ECO: ECO: Multicystic variant: a multicystic mass with cysts of various sizes. Multicystic variant: a multicystic mass with cysts of various sizes. Solid variant: a large and heterogeneous mass, hypoechoic to moderately echogenic, with irregular anechoic areas (central necrosis and hemorrhage). Solid variant: a large and heterogeneous mass, hypoechoic to moderately echogenic, with irregular anechoic areas (central necrosis and hemorrhage). FEATURES: -It crosses the midline -It has an expansive growth well-defined compressed renal tissue forming a pseudocapsule move the vessels, rather than encapsulated -with calcifications in 5-15% of the tumors -It may invade the renal vein and inferior vena cava (4-10%), and extended to the right atrium

33. Abdominal CT : Abdominal CT : It helps in determining the origin of the tumor, involvement of the lymph nodes, bilateral kidney involvement, invasion into major vessels (eg, inferior vena cava), and liver metastases. It helps in determining the origin of the tumor, involvement of the lymph nodes, bilateral kidney involvement, invasion into major vessels (eg, inferior vena cava), and liver metastases. FEATURES: FEATURES: a heterogeneous mass located in the kidney with a rim of enhancing renal tissue around the lower attenuation mass. a heterogeneous mass located in the kidney with a rim of enhancing renal tissue around the lower attenuation mass. It is well circumscribed with cystic areas with hemorrhage, necrosis, fat and calcifications. It is well circumscribed with cystic areas with hemorrhage, necrosis, fat and calcifications.

34. OTHER: 4. Pseudocyst due to ventriculo-peritoneal derivation. Usually there is a small / moderate amount of intraperitoneal free fluid. Usually there is a small / moderate amount of intraperitoneal free fluid. When there is loculated fluid around the catheter tip, it forms a pseudocyst. When there is loculated fluid around the catheter tip, it forms a pseudocyst. US: US: An anechoic or hypoechoic liquid collection An anechoic or hypoechoic liquid collection Well defined Well defined It produces mass effect on adjacent abdominal structures and organs. It produces mass effect on adjacent abdominal structures and organs. If it is infected: detritus and septa inside If it is infected: detritus and septa inside

35. A. A 15-year-old with pain and abdominal distension. A B B. A 4-year-old with a left abdominal mass. US Coronal contrast-enhanced CT Sagital contrast-enhanced CT

36. Conclusion: Various cases of abdominal cystic masses are presented, reviewing radio-pathological features and differential diagnosis. Various cases of abdominal cystic masses are presented, reviewing radio-pathological features and differential diagnosis. Imaging features, along with the patient's age and the clinical history, allow a narrow differential diagnosis and guide therapy decisions. Imaging features, along with the patient's age and the clinical history, allow a narrow differential diagnosis and guide therapy decisions.

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