Renal Tumors Overview

Renal Tumors - Learning Objectives

• Classify kidney tumors
• Classify urinary bladder tumors
• Discuss kidney and bladder carcinoma pathogenesis
• Discuss the various carcinomas' morphology (renal carcinoma, Wilm's tumor, and bladder carcinoma)

Tumors of the Kidney

• Benign:
  • Epithelial: Cortical adenoma, Oncocytoma
  • Mesodermal: Renal fibroma or hamartoma, Angiomyolipoma, Lipoma, leiomyoma, myxoma, hemangioma, and lymphangioma
• Malignant:
  • Primary epithelial: Renal cell carcinoma
  • Primary Mesodermal: Sarcoma, lymphomas, and Wilm's tumor (nephroblastoma)
  • Secondary: Direct or lymphatic spread, blood stream metastasis

Tumors of the Renal Pelvis

• Benign:
  • Epithelial: Papilloma, inverted papilloma
  • Mesodermal: Leiomyoma, neurofibroma, hemangioma (capillary or cavernous)
• Malignant:
  • (a) Transitional cell carcinoma
  • (b) Squamous cell carcinoma

Renal Cell Carcinoma (Adenocarcinoma)

• Incidence: 1-3% of visceral cancers, 85% of renal cancers in adults; more common in males, ages 40-70
• Origin: Epithelium of renal tubules or cortical adenoma

Risk Factors

• Tobacco (most significant, doubles incidence)
• Obesity
• Hypertension
• Unopposed estrogen therapy
• Long-term renal dialysis
• Exposure to arsenic, asbestos, petroleum products, and heavy metals
• Chronic renal failure, acquired cystic disease, tubular sclerosis
• Genetic factors

Etiology of RCC

• Sporadic: Most common
• Familial: Autosomal-dominant familial cancer
  • Hereditary (familial) clear cell carcinoma: Confined to kidney involving VHL gene, bilateral, often multiple renal cell carcinomas of clear cell type
  • Hereditary papillary carcinoma: Multiple, bilateral tumor, papillary histology

Classification of Renal Cell Carcinoma

1. Clear cell RCC
2. Papillary RCC
3. Chromophobe RCC
4. Collecting duct carcinoma

Clinical Effects

• Painless hematuria
• Pain in loin
• Palpable mass
• Paraneoplastic syndromes: Hypercalcemia, polycythemia, hypertension, hepatic dysfunction, feminization, masculinization

Spread of the Tumor

• Direct: To renal medulla, renal capsule to surrounding structures, and renal vein to inferior vena cava
• Blood spread: Early to lung, bone, and liver
• Lymphatic spread: To para-aortic lymph nodes

1- Clear RCC

• Incidence & Pathogenesis: Most common (70-80%), may be familial or associated with VHL disease, or mostly sporadic (95%)
• Loss of sequences of the short arm of chromosome 3 occurs by deletion or unbalanced translocation (3,6-3,8-3,11), or somatic mutations; VHL gene acts as a tumor suppressor gene (in 80% of clear cell renal cell carcinoma)

Gross Picture

• Site: Mostly from proximal tubular epithelium; commonly affects the upper pole
• Shape: Solitary, unilateral, spherical mass; size varies
• Color: Bright yellow (due to lipid accumulation)
• C/S: Gray-white with large areas of ischemic opaque necrosis, foci of hemorrhage, and areas of softening; margins are sharply defined

Microscopic Picture

• Solid trabecular or tubular pattern
• Round or polygonal cells with abundant clear or granular cytoplasm
• Have delicate branching vasculature; may be with cystic & solid areas
• Mostly differentiated but may show nuclear atypia, bizarre nuclei, & giant cells

2- Papillary RCC

• Incidence & Pathogenesis: 10-15%, occurs in both familial and sporadic forms, associated with 3p deletions, common trisomies 7, 16, 17, loss of Y in males with sporadic forms and trisomy 7 in familial forms, papillary RCC has 2nd gene on chromosome 1 in sporadic forms, [x,1] translocation

Gross Picture

• Arise from distal convoluted tubules
• Multifocal, bilateral
• Hemorrhagic, cystic
• Enlarges, bulges into calyces and pelvis; may fungate through the walls of collecting systems; may enter ureter
• High tendency to invade the renal vein, grow as a solid column; may extend to inferior vena cava, even the right side of the heart

Microscopic Picture

• Cuboidal or low columnar cells arranged in papillary formation
• In the papillary core, interstitial foam cells
• Psammoma bodies
• Stroma is scanty but highly vascular
• In the core of papillary RCC; neutrophils, foam histiocytes, blastemal component, malignant spindle cells, plasma cells

Chromophobe RCC

• Incidence & Pathogenesis: 5% with multiple chromosomal losses

• Originates from epithelium lining the cortical part of collecting ducts

• Gross: Solid tumor, light brown cut surface

• Microscopic: Large cells with prominent cell membranes, pale eosinophilic cytoplasm with perinuclear halo; solid sheets; concentration of cells around blood vessels

Collecting Duct (Bellini Duct) Carcinoma

• Incidence & Pathogenesis: 1% or less, numerous chromosomal losses and deletions, arises from medullary part of collecting ducts; aggressive behavior
• Gross: Rare variant; usually located in the medulla of the kidney
• Microscopic: Irregular channels or tubules lined by highly atypical epithelial cells with a hobnail pattern

Wilm's Tumor (Nephroblastoma or Embryoma)

• Definition: Childhood tumor derived from renal blastema
• Incidence: Peak incidence 2-4 years old; constitutes 20% of malignant tumors in children; bilateral in 5-10% of cases

Morphology

• Gross: Large, rounded or lobulate, well-circumscribed; soft consistency, pale gray cut section with cystic changes

Microscopic Picture

• Cellular nests and sheets of primitive blastemal cells, round or oval with scanty cytoplasm
• Mesenchymal component of fibrous tissue, smooth muscle, striated muscle, bone, and cartilage
• Epithelial component of embryonic tubules and glomeruloid structures

Clinical Features

• Large abdominal mass
• Hematuria and pain in abdomen after trauma
• Combined radiotherapy, chemotherapy, and surgery markedly reduces recurrence rate

Spread

• Local infiltration of kidney capsule and surrounding structures
• Blood spread early to lung, liver, bone, and brain
• Lymphatic spread to para-aortic lymph nodes

Staging of Pediatric Renal Cell Tumors

• Stage I: Limited to kidney and completely resected
• Stage II: Infiltrates beyond kidney but completely resected
• Stage III: Residual non-hematogenous tumor confined to the abdomen
• Stage IV: Hematogenous metastasis
• Stage V: Bilateral renal involvement at diagnosis

Transitional Cell Carcinoma of the Renal Pelvis

• Small tumors that block urinary outflow, leading to palpable hydronephrosis and loin pain
• Histologically, the exact counterpart of those found in the urinary bladder; 50% of cases have preexisting or concomitant bladder urothelial tumor

Tumors of the Ureter

• Primary neoplasia very rare, but metastatic spread is common
• Benign: Mesenchymal origin (fibrous tissue, muscle, blood vessels, lymphatic); examples include: fibroepithelial polyp, leiomyoma
• Malignant: Urothelial origin (transitional cell carcinoma); secondaries

This quiz covers key learning objectives related to renal tumors, including classifications of kidney and bladder tumors. It discusses the pathogenesis and morphology of various carcinomas such as renal cell carcinoma and Wilm's tumor. Test your understanding of the different types of tumors found in the kidneys and urinary bladder.