Pediatric Abdominal Mass Discussion Pediatric Abdominal Mass

Wilms’ tumor Undifferentiated metanephric blastema Most common malignant abdominal neoplasm in children 1-8 years old (10%) 3rd most common malignancy in childhood (after leukemia + brain tumors; neuroblastoma more common in infancy)!

Incidence:1:10,000 livebirths; familial in 1-2%; multifocal in 10%; bilateral in 4.4-9% Age:peak age at 2.5-3 years (range of 3 months to 8 years) rare during first year; 50% before 3 years, 75% before 5 years; 90% before 8 years; rare in adults; M:F = 1:1

Clinical evalution Palpable abdominal mass, usually unilateral (90%) Hypertension (47-90%) Abdominal pain (25%), fever (15%), hematuria (7-15%) Paraneoplastic syndromes Congenital anomaly (15%)

Radiologic evaluation Plain film: US: CT: -- Unenhanced : round, well-defined, solid, less dense, intrarenal mass -- Distortion of collecting system -- Calcification 15% -- Partially cystic = focal hemorrhage and necrosis (71%) -- Enhanced: inhomogenous, less dense MR: hypointense on T1WI, variable on T2WI

Mass displacing adjacent bowel or collecting system Calcification(5%)

fairly evenly echogenic mass ± irregular anechoic areas due to central necrosis + hemorrhage

Treatment and prognosis Treatments for Wilms' tumor depend on the stage of your child's disease, the cell type (histology), and your child's age and general health. Surgery, CT, and RT Prognosis:90% survival rate depending on pathologic pattern, age at time of diagnosis, extent of disease

Neuroblastoma Origin: neural crest Most common solid abdominal mass of infancy (12.3% of all perinatal neoplasms), 3rd most common malignant tumor in infancy (after leukemia + CNS tumors), 2nd most common tumor in childhood (Wilms tumor more common in older children), 7% of all childhood cancers; 15% of cancer deaths in children

Incidence:1:7,100 to 1:10,000 livebirths; 20% hereditary Age: peak age at 2 years; 25% during 1st year; 50% <2 years; 75% in <4 years; 90% in <8 years; occasionally present at birth; M:F = 1:1 Location: anywhere within sympathetic neural chain

Clinical evaluation Palpable, firm, irregular, slightly tender abdominal mass, often cross the midline Hypertension (up to 30%) Silent until invasion or compression adjacent structures: -- Edema of legs, constipation, oligouria, radicular pain or paraplegia Fever, weight loss, and gerenalized pain

Metastases: bone (60%), regional lymph nodes (42%), orbit (20%), liver (15%), intracranial (14%), lung (10%) Encase the great vessels Paraneoplastic syndrome: -- opsoclonus - myoclonus syndrome -- Intractable watery diarrhea

Increased 24-hour urinary levels of catecholamine metabolites Elevated Dopamine Bone marrow aspirate positive in 50-70% at time of initial diagnosis

Radiologic evaluation Plain film: mass, calcification (50%) US: hyper- / hypoechoic mass with acoustic shadows CT: calcification(60%) -- Enhanced : irregular, lobulated, unencapsulated, inhomogeneous tumor, often with central necrosis -- encasement of IVC + aorta, celiac axis, SMA (32%) MRI: low on T1 and high on T2, uniform and well-defined

Neuroblastoma VS Wilms’ tumor Predominant suprarenal mass Growth across the midline Multifocal calcification within mass Displacement of the great vessels

Treatment and Prognosis Complete resection is difficult due to vascular invasion Multiple chemotherapy or radiation therapy Prognostic factor: Age, stage and location 2-year survival rate versus age at presentation: -- 60%if patients age<1year -- 20%if patients age1-2years -- 10%if patients age>2years

HEPATOBLASTOMA Incidence: 3rd most common abdominal tumor in children; most frequent malignant hepatic tumor in children (51%) Age: <3 years; <18 months (in 50%); peak age between 18 and 24 months; range from newborn to 15 years; M:F = 2:1 --epithelial type = small cells resembling embryonal / fetal liver --mixed type = epithelial cells + mesenchymal cells

Clinical evaluation Upper abdominal mass Weight loss, nausea, vomiting Precocious puberty (production of endocrine substances) Persistently + markedly elevated AFP (66%) Metastases to: lung (frequent)

Location: right lobe of the liver Usually solitary mass with an average size of 10-12 cm Coarse calcifications / osseous matrix (12-30%) US: -- large heterogeneous echogenic mass, sometimes with calcifications, occasionally cystic areas (necrosis / extramedullary hematopoiesis) CT: -- hypointense tumor with peripheral rim enhancement

MR: -- inhomogeneously hypointense on T1WI with hyperintense foci (hemorrhage) -- inhomogeneously hyperintense with hypointense bands (fibrous septa) on T2WI Angio: -- hypervascular mass with dense stain -- NO AV-shunting -- vascular lakes may be present -- may show caval involvement (= unresectable)

Treatment and Prognosis Complete excision 50%~60% Adjuvant chemotherapy Prognosis:60% resectable; 75% mortality; better prognosis than hepatoma; better prognosis for epithelial type than mixed type