Mesoblastic Nephroma: Radiographic Characteristics, Diagnosis, and Treatment

1. CASES Dr Mayur Pankhania, R2 Dept of Radiodiagnosis SSG Hospital.( 6/12/07 )

2. Case 1

3. 10 month old boy with hematuria • USG : shows hetrogenous hypo to anechoic mass lesion in the left kidney.

6. Axial contrast-enhanced CT scan demonstrates a large left renal mass (arrows) with heterogeneous enhancement. Noted are subcapsular fluid collections. • b Axial CT scan through the chest identifi es multiple foci of metastatic disease (arrows).

7. D/D Rhabdoid tumor Wilms tumor Mesoblastic Nephroma.

8. Mesoblastic Nephroma • Also k/a FETAL RENAL HAMARTOMA = LEIOMYOMATOUS HAMARTOMA • nonfamilial benign fibromyomatoid mass arising from renal connective tissue. • Incidence:most common solid renal neoplasm in neonate; 3% of all renal neoplasms in children • Age:peak age 1-3 months; 90% within 1st year of life; rare after the age of 6 months • M > F • associated with: prematurity, polyhydramnios, GI + GU tract malformations, neuroblastoma

9. C/F: • large palpable flank mass (most common) • hematuria (20%) / hypertension (4%), anemia • large solid intrarenal mass: • usually replaces 60 to 90% of renal parenchyma • typically involves renal sinus • may produce multiple cystic spaces (hemorrhage, necrosis) • infiltrative growth: • NO sharp cleavage plane toward normal parenchyma • may extend beyond capsule (common) • Calcifications (rare) • NO venous extension (DDx from Wilms tumor) • NO invasion of collecting system

10. IVP: • large noncalcified renal mass with distortion of collecting system • usually NO herniation into renal pelvis. • US: • solid intrarenal mass that often extends into the renal sinus • evenly echogenic tumor resembling uterine fibroids • concentric rings of alternating echogenicity • large masses present as complex heterogeneous mass with hemorrhage + cyst formation + necrosis • CT • focal perinephric space infiltration • uniform enhancement of less than normal renal parenchyma • areas of low attenuation in large lesions (hemorrhage / necrosis)

11. Longitudinal US image reveals a mixed echo texture mass (arrow) replacing most of the right kidney. b Axial CECT scan reveals a hypodense, ill-defined, infiltrative, right renal mass (arrow) which uniformly enhances but less then that renal paranchyma. A c/o Mesoblastic nephroma

12. On T1-W MR images, a low signal mass arising form the kidney without caval extension • OB-US: • polyhydramnios, hydrops • Angio: • hypervascular mass with neovascularity + displacement of adjacent vessels

13. Cx: • (1) Transformation to metastasizing spindle cell sarcoma (rare)  • (2) Metastases to lung, brain, bone (rare) • Rx: • nephrectomy with wide surgical margin (is necessary due to the infiltrative nature of the lesion which may recur locally if incompletely resected ) • Prognosis: • excellent (imaging follow-up for 1 year)

14. Wilms tumor • k/a NEPHROBLASTOMA • Most common malignant abdominal neoplasm in children • 3rd most common malignancy in childhood (after leukemia + brain tumors; neuroblastoma more common in infancy) • Usually Unilateral, bilateral 10% • Age: • peak age at 3-4 years (range of 3 months to 11 years); rare during first year • M:F = 1:1

15. While the etiology remains unknown, the pathophysiology of WT is characterized by an abnormal proliferation of the metanephric blastema (primitive embryonal renal tissue). • The tumor may arise in three clinical settings: • sporadic; • association with genetic syndromes; and • familial.

16. C/F • asymptomatic palpable abdominal mass (90%) • hypertension (in up to 25%) due to renin production by tumor / vascular compression by tumor • abdominal pain (25%) • low-grade fever (15%) • gross hematuria with invasion of renal pelvis • microscopic hematuria (15-25%) • hemorrhage after minor trauma • ascites due to venous obstruction • varicocele from left-sided tumor • RULE OF 10's: • 10% unfavorable histology • 10% bilateral • 10% vascular invasion • 10% calcifications • 10% pulmonary metastases at presentation

17. Imagine Features General: • large tumor (average size 12 cm) • expansile growth, sharply marginated with compression of renal tissue= pseudocapsule • Distorted / dilated calyces • displacement of major vessels, rather than encasement • curvilinear / phlebolithic calcifications • tumor invasion of renal vein and IVC (4-10%); extension into right atrium (in 21% of cases with IVC invasion) • tumor may cross midline • poor / non excretion of IV contrast due to invasion or compression of hilar vessels + collecting system / extensive tumor infiltration of renal parenchyma

18. US: • predominantly solid spherical mass: • heterogeneous echogenicity (frequent): • irregular anechoic areas due to central necrosis + hemorrhage + cyst formation • echogenic areas representing fat / calcium • fairly evenly echogenic (rare) • CT (preferred modality): • well-circumscribed heterogeneous partially cystic mass due to focal hemorrhage and necrosis (71%), cyst formation, fat, calcification • beak / claw of renal tissue extends partially around mass • tumor less enhancing than renal parenchyma • nodal / hepatic metastases • tumor extension into renal vein / IVC • contralateral synchronous tumor/ nephrogenic rests

19. Ultrasound shows a large heterogeneous right renal mass. Normal color Doppler venous waveforms are identified within the IVC.

20. Coronal CECT of abdomenshows a large nonhomogeneous enhancing right renal mass that mildly displaces the inferior vena cava and right renal vein inferomedially. However the IVC and right renal enhance normally, without evidence of vascular extension or thrombus. No evidence of periportal, mesenteric, or retroperitoneal lymphadenopathy.

21. MR: • hypointense on T1WI • high / variable intensity on T2WI • NUC: • nonfunctioning kidney (10%) • hypo- / iso- / hyperperfusion on radionuclide angiogram • absent tracer accumulation on delayed static images • displacement of kidney + distortion of collecting system • Angio: • hypervascular tumor: enlarged tortuous vessels, coarse neovascularity; small arterial aneurysms, vascular lakes

22. Stage of Wilms Tumor ( National Wilms' Tumor Study Group) • I tumor limited to kidney (renal capsule intact) • II local extension beyond renal capsule into perirenal tissue / renal vessels outside kidney / lymph nodes • III not totally resectable (peritoneal implants, other than paraaortic nodes involved, invasion of vital structures) • IV hematogenous metastases (lung in 85%, liver in 7%, bone in 0.8%, brain [rare]) / lymph node metastases outside abdomen or pelvis • V bilateral renal involvement at diagnosis (4-13%)

23. Rx: • presurgical chemotherapy + nephrectomy + adjuvant chemotherapy ± radiation therapy • Prognosis: • survival rate depending on pathologic pattern, age at time of diagnosis, extent of disease

24. RHABDOID TUMOUR • Rare, highly aggressive renal malignancy of childhood. • Worst prognosis of all renal tumour. • age:11-17 months; • M:F = 1.5:1 • Origin: renal sinus • Histo:filamentous intracytoplasmic inclusions (CHARACTERISTIC) • Early Metastatic to:lung, liver, brain ( most pt present with adv dz)

25. Associated with: • metachronous primary brain tumor of neuroectodermal origin (medulloblastoma, ependymoma, cerebellar / brainstem astrocytoma, PNET) ( midline and Post fossa ) C/F: • Presenting symptoms are nonspecific, but may include: • hematuria, • an abdominal mass, or • symptoms related to metastatic disease. • Elevated serum calcium (hypercalcemia secondary) due to increased parathyroid hormone levels may be found. These levels normalize following tumor resection.

26. Radiological feature: • centrally located large heterogeneous renal mass: • indistinct borders with infiltration of medulla + sinus (tumor lobules separated by hypodense areas of necrosis or hemorrhage) • PROMINENT peripheral crescent-shaped subcapsular fluid collection in 70% (subcapsular hematoma in 47% / necrotic cavity in 53%) • linear calcifications outlining tumor lobules • There may be vascular and local invasion of structures • midline posterior fossa mass in brain. • metastases (in 80%) to lung, liver, abdomen, brain, lymph nodes, bone

27. Subcapsuiar hematoma in rhabdold tumor of kidney in 1 5-month-old female. CT scan shows large area of crescent-shaped hypodensity in kidney periphery, whIch proved to be subcapsular hematoma at surgery. This is seen in 44% of rhabdoid tumors but is rare in other renal tumors. Also note involvement of hilum with central location of tumor within kidney.

28. Postcontrast CT scan shows lobular appearance of tumor nodules separated by central areas of hemorrhage and necrosis. Areas of hemorrhage and necrosis tend to outline tumor nodules, unlike Wilms’ tumor, in which areas of hemorrhage and necrosis are more rounded and do not circumscribe tumor lobules.

29. Calcification in rhabdoid tumor in 1- day-old female. Noncontrast CT scan shows areas of fine hyperdensity (arrow) that correspond to calcification on histologic examination. Calcifications in rhabdoid tumors appear linear and tend to outline tumor lobules, unlike small patchy calcificatlonsin Wiims’ tumors.

31. Case 2

32. A 68-year-old female patient presented with two weeks of nonproductive cough.

36. Findings • A chest radiograph showed an outpouching along the left border of the left cardiac silhouette • A computed tomography (CT) scan of the thorax showed the presence of a left atrial mass CT scan of the thorax shows a left atrial mass (arrowhead) and a probable pericardial cyst (arrow). • The former lesion was confirmed on transthoracic echocardiography and then transesophageal echocardiography which demonstrated a well-defined mobile nonhomogenous mass (dimensions, 1.3 x 1.2 cm) with a broad base of0.5 cm attached to the posterior wall of the left atrium.

37. Cardiac catheterisation, performed prior to cardiac surgery, excluded any underlying occultcoronary artery obstructive disease, but demonstrated neovascularisation of the mass from the sinoatrial nodal branch of the right coronary artery. Coronary angiogram shows neovascularisation of the myxoma (large arrows) and its arterial blood supply (small arrows).

38. Gross appearance of the myxoma which was removed during surgery.

39. Diagnosis • Left atrium myxoma with pericardial cyst.

40. Myxoma • most common benign primary cardiac tumor (true neoplasm) in adults, 40-50% of all cardiac tumors. • Age: 11-82 (mean 50) years; 90% of patients are between ages 30 and 60 years; • M:F = 1:1.7 to 1:4 • Classification: • sporadic (most frequent); • familial type (mean age of 24 years); • complex type = Carney syndrome

41. Site of origin : • left atrium ( 75% ), • right atrium( 15-20%); • ventricles (<10%) • Pt present with triad of • cardioembolism, • intracardiac obstruction, or • nonspecific constitutional manifestations.

42. LEFT ATRIAL MYXOMA (75-80%) with obstruction of mitral valve: • pulmonary venous hypertension: • pulmonary vascular redistribution • interstitial edema • enlargement of LA • NO enlargement of atrial appendage • Cx:systemic emboli (27%) in 50% to CNS (stroke/mycotic aneurysm) • RIGHT ATRIAL MYXOMA (10-20%) with obstruction of tricuspid valve: • tumor calcification: R > L • enlargement of RA • prominent SVC, IVC, azygos vein • decreased pulmonary vascularity • pleural effusion (occasionally) • Cx:pulmonary emboli

43. X-ray: • small myxomas produce no CXR findings • Cardiomegaly • Atrial obstruction (mimicking valvular stenosis) • ECHO: (2D-ECHO is study of choice) • tumor attached by narrow stalk • tumor mobility: • prolapse across AV valve during diastole • tumor distensibility • hyperechoic spherical mass: • internal hypoechoic areas (= hemorrhage, necrosis) • speckled echogenic foci (= calcifications) • frondlike surface projections • Doppler: • valvular regurgitation

44. Transthoracic apical view of a left atrial myxoma. Biplane transesophageal view showing simultaneous transverse and longitudinal planes of a left atrial myxoma. The stalk is visible in the longitudinal plane.

45. CT: • well-defined spherical/ovoid intraluminal filling defect • lobular/smooth surface contour • tumor attenuation lower than unopacified blood (due to gelatinous component) • heterogeneous texture (due to hemorrhage, necrosis, cyst formation, fibrosis, calcification [16%], ossification)

47. MR: • iso-/hypointense on T1WI relative to myocardium • markedly hyperintense on T2WI • heterogeneous contrast enhancement (secondary to necrotic areas) • areas of decreased signal intensity (calcifications, hemosiderin deposits)

48. T1-weighted &T2- W MRI images show a small myxoma (arrow in a) arising from the posteriorwall of the left atrium (LA). The lesion has a heterogeneous appearance on the T1-weighted image (a) and almosthomogeneous high signal intensity on the T2- weighted image (b). (c) Axial T1W MRI obtained 20 minutes after administration of gadolinium contrast material, shows heterogeneous intense enhancement of the lesion with areas of delayed enhancement peripherally due to necrosis (arrows). LV left ventricle.

49. D/D • Thrombus (most commonly in LA + LV) • Other cardiac tumors: • Benign: • myxoma • Fibroma • lipoma • Papillary Fibroestastoma • Rhabdomyoma • Paraganglioma • Teratoma • Malignant: • angiosarcoma • Lymphoma • mesothelioma

50. Thrombus • Left Atrial Thrombus • Associated with:mitral valve disease & atrial fibrillation • Site:atrial appendage, most in posterior location,( Cx Myxoma from interatrial septum ) • Left Ventricular Thrombus • Site:region of ventricular dyskinesia/aneurysm (from prior myocardial infarction) • RF : • causes dilation of involve chamber • irregular/lobulated border • microcavitations • laminated appearance • homogeneous attenuation on CT (Myxoma,heterogeneous texture on CT)