renal system

Tumors Of The Kidney

Benign Tumors :They rarely cause clinical problems. Renal Papillary Adenoma Renal Fibroma or Hamartoma. Malignant Tumors : On the contrary to benign tumors, malignant tumors are clinically of great importance

Pediatric Tumors And Tumor-Like Conditions1/Nephroblastoma (Wilm’s Tumor) It is seen primarily in infants and children. There is no sex predilection. The classical clinical presentation in form of an abdominal mass, hematuria and pain are rare. Other features include; hypertension, proteinuria and sometime tumor rupture.

Morphologic features

Grossly: Tumors are solitary, well circumscribed, rounded and of soft in consistency. The size is variable, with a median weight of 550gm. The cut section is predominantly solid and pale gray or tan and often exhibits areas of cystic change, necrosis, and hemorrhage. Multicentric foci are found in 7% of cases.

Microscopically: Three major components are identified 1. Undifferentiated blastema. 2. Mesenchymal (stromal) tissue. 3. Epithelial tissue. Anaplastic features may be present focally or extensively.

Molecular genetic features

The genetic loci predisposing to nephroblastoma are: WT1 located on 11p13. WT2 located on 11p15.5. Other chromosomal abnormalities include, 1, 7q, 12, & 16.

Mesoblastic Nephroma

It is congenital renal neoplasm, usually discovered in patients before they reach 6 months of age. Grossly, the tumor is solid, yellowish/grayish to tan with a whorled configuration. Microscopically: A variably cellular growth of spindle cells is the predominant feature. The large majority of mesoblastic nephromas are cured following nephrectomy. In up to 7% of the cases, recurrence may develop.

Adult Tumors And Tumor-Like Conditions:1/Renal Cell Carcinoma

Average age at diagnosis is 55-60 years. Rarely may occur during childhood. The M:F ratio is 2:1, Epidemiology, there are many risk factors;1. Tobacco is the most significant factor.2. Obesity, particularly in women.3. Hypertension.4. Unopposed estrogen therapy.5. Exposure to, asbestos, petroleum products, and heavy metals.


Conditions that may be complicated by renal cell carcinoma are the followings; 1. von-Hippel-Lindau (VHL) disease, renal cell carcinoma occurs in more than 50% of individuals with this syndrome. 2. Acquired cystic renal disease, about 50% of the patients on long-term dialysis develop renal cysts, 7% of cases are complicated by cancer. 3. Adult form of polycystic kidney disease and multicystic nephroma. 4. Lymphoma.

Clinical features

It usually presents with hematuria, flank pain or abdominal mass. However, this diagnostic triad occurs in only 9% of the patients. Other manifestations are weight loss, anemia, fever, and symptoms caused by metastatic deposits. Rarely paraneoplastic manifestations may occur.

Morphologic features

Grossly, most renal cell carcinomas are well delineated and cortical in location. Usually the cut surface is solid golden/yellow in color. Areas of hemorrhage, necrosis, calcification, and cystic change are common findings. Microscopically, tubular and glandular growth of tumor cells with large nuclei, and cytoplasm ranging from granular to clear.

Other microscopic type

Papillary renal cell carcinoma, It comprises about 15% of all cases of renal cell carcinoma. Renal tumors arising in patients on chronic hemodialysis are of this type. Microscopically, complex papillary formations are seen, and psammoma bodies are numerous. Stroma is heavily infiltrated by neutrophils and foamy macrophages. As a group, papillary renal cell carcinoma has a better prognosis than conventional RCC

Spread and metastasis

About 1/3 of renal cell carcinomas are found to invade perinephric fat and/or regional lymph nodes at the time of operation. Renal vein invasion is seen on only 10% of cases. Approximately 1/3 of patients with renal cell carcinoma already have distant metastases at the time they seek medical advice, lung and skeleton, being the most common sites. Metastases can also develop in the adrenals, liver, skin, soft tissue, CNS, ovary, and almost any other site. Sometimes, these metastases develop years or decades after the removal of the primary tumor.

Oncocytoma

Oncocytomas make up approximately 7% of all primary nonurothelial epithelial renal neoplasms. Grossly, they are typically solid and mahogany brown, often have a central stellate scar, and can reach huge sizes. Microscopically, are composed of entirely of cells with abundant acidophilic granular cytoplasm, arranged in alveolar or tubular fashion.

Angiomyolipoma

Most patients are adults. Approximately 1/3 of the patients with this tumor suffer from tuberous sclerosis Grossly, the tumor may closely simulate renal cell carcinoma, because of the admixture of yellow areas and hemorrhagic areas. Microscopically, there is admixture of mature adipose tissue, tortuous thick-walled blood vessels, and bundles of smooth muscle


Tumors of Renal Pelvis and Ureters
Transitional Cell Carcinoma;Most cases occur in adults. There is a history of analgesic abuse and/or coexistence of renal papillary necrosis in approximately 1/4 of cases. Cases have been seen following administration of thorotrast  Grossly, the tumors are soft, grayish/reddish masses, often diffusely involving the entire renal pelvis and may extend to the ureters. Tumors of the ureters might be located anywhere along their length.