Sandbox SSW

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sargun Singh Walia M.B.B.S.[2]

Differential Diagnosis

S.No.	Disease	Symptoms			Signs		Diagnosis			Comments
		Abdominal Pain	Hematuria	Headache	Abdominal mass	Abdominal tenderness	Ultrasonography	CT scan	Histology
1.	Wilms tumor	+	+	-	+	+	It is the best initial diagnostic study used in cases suspected with wilms tumor. Ultrasonography can help identify the mass as a kidney mass. It can distinguish tumor mass from other causes of renal swelling like hydronephrosis. Doppler ultrasonography can help to detect invasion of renal vein and IVC by the tumor.	Findings on CT scan which can be suggestive of wilms tumor include: Heterogeneous soft-tissue density masses These masses have frequent areas of calcification (~10%) and fat-density regions Lymph node metastasis CT scan of the renal mass can further reveal: Invasion of surrounding organs Thrombus in or occlusion of the renal vein and/or the inferior vena cava Abdominal lymph nodes and contralateral involvement	Wilms tumor has a triphasic appearance. It is comprised of 3 types of cells: Stromal Epithelial Blastemal All the 3 types are not required for the diagnosis of Wilms tumor. Primitive tubules and glomeruli are often seen comprised of neoplastic cells. Beckwith and Palmer reported in NWTS the different histopathologic types of Wilms tumor to categorize them based on prognosis. Spindled cell stroma surrounding abortive tubules and glomeruli is characteristic. The stroma may include: Striated muscle cartilage bone Fat tissue Fibrous tissue.
2.	Clear cell sarcoma
3.	Renal cell carcinoma						Ultrasound (US) may be helpful when CT scan results are equivocal. It is noteworthy to mention that not all renal cell carcinomas are detectable on ultrasound.	Both CT and MRI may be used to detect neoplastic masses that may define renal cell carcinoma or metastasis of the primary cancer. CT scan and use of intravenous (IV) contrast is generally used for work-up and follow-up of patients with renal cell carcinoma.	The histological pattern of renal cell carcinoma depends whether it is papillary, chromophobe or collecting duct renal cell carcinoma.
4.	Rhabdoid kidney disease							CT scan may be diagnostic of malignant rhabdoid tumor. Findings on CT scan suggestive of malignant rhabdoid tumor include a large, heterogenous, centrally located mass, which is lobulated with individual lobules separated by intervening areas of decreased attenuation, relating to either previous hemorrhage or necrosis. Enhancement is similarly heterogeneous. Calcification is relatively common, observed in 20-50% of cases and is typically linear and tends to outline tumur lobules.	Malignant rhabdoid tumor is characterized by the round blue tumor cells of high cellularity composed of atypical cells with eccentric nuclei, small nucleoli, and abundant amounts of eosinophilic cytoplasm with frequent mitotic figures.
5.	Polycystic kidney disease						Ultrasound may be helpful in the diagnosis of polycystic kidney disease. Findings on an ultrasound diagnostic of polycystic kidney disease include: At least three unilateral or bilateral cysts in patients 15 - 39 years old Atleast two cysts in each kidney in patients 40 - 59 years old Atleast four cysts in each kidney in patients 60 years of age or older	Renal CT scan may be helpful in the diagnosis of polycystic kidney disease. Findings on CT scan diagnostic of ADPKD include: Numerous renal cysts of varying size and shape with little intervening parenchyma with water attenuation and very thin wall. Reduction in sinus fat due to expansion of the cortex Occasional complex cysts with hyperdense appearance, with possible septations or calcifications Multiple homogeneous and hypoattenuating cystic lesions in the liver in patients with liver involvement	On microscopic histopathological analysis, interstitial fibrosis, tubular atrophy, thickening and lamellation of tubular basement membranes, microcysts and negative immunofluorescence for complement and immunoglobulin are characteristic findings of ADPKD.
6.	Pheochromocytoma							The following findings may be observed on CT scan: Most common extra-adrenal locations are superior and inferior abdominal paraaortic areas, the urinary bladder, thorax, head, neck and pelvis. In sporadic pheochromocytoma, CT and MRI are good choices. The choice depends on availability and cost. In patients with the multiple endocrine neoplasia type 2 (MEN2) syndrome, CT may miss the tumors.	On microscopic pathology, Pheochromocytoma typically demonstrates a nesting (Zellballen) pattern on microscopy. This pattern is composed of well-defined clusters of tumor cells containing eosinophilic cytoplasm separated by fibrovascular stroma.
7.	Burkitt lymphoma						Abdominal US may show splenomegaly and ascites.	Chest, abdomen, and pelvis CT scan may be helpful in the diagnosis of Burkitt's lymphoma but it is not done routinely.	On microscopic histopathological analysis, characteristic findings of Burkitt's lymphoma include: Medium-sized (~1.5-2x the size of a RBC) with uniform size ("monotonous") -- key feature (i.e. tumor nuclei size similar to that of histiocytes or endothelial cells) Round nucleus Small nucleoli Relatively abundant cytoplasm (basophilic) Brisk mitotic rate and apoptotic activity Cellular outline usually appears squared off "Starry-sky pattern": The stars in the pattern are tingible-body macrophages (macrophages containing apoptotic tumor cells) The tumour cells are the sky
8.	Intussusception						Ultrasound is the gold standard imaging modality used to diagnose intussusception Target or doughnut sign Edematous intussuscipien forms an external ring around the centrally located intussusceptum Target sign is usually seen in right lower quadrant Layers of intussusception forms pseudo-kidney appearance on the transverse view	CT scan may be helpful in the diagnosis of intussusception. CT scan maybe used when other image modalities like x-ray and ultrasound have not given positive results but suspicion of intussusception is high.
9.	Hydronephrosis
10.	Renal cyst
11.	Renal thrombosis
12.	Dysplastic kidney
13.	Renal hemorrhage
14.	Pediatric Neuroblastoma
15.	Pediatric Rhabdomyosarcoma
16.	Mesoblastic nephroma									Most common renal tumor that occurs in 1st month of life