Renal tumors Dr. Abdelaty Shawky Dr. Gehan Mohamed

Learning objectives 1. List the classification of renal tumors. 2. Describe renal oncocytoma. 3. Describe renal cortical adenoma. 4. Discuss risk factors for renal cell carcinoma. 5. Discuss clinical presentation of RCC. 6. list the different histologic subtypes of RCC. 7. understand the TNM staging, grading of RCC. 8. Recognize the pathological features of Wilms tumor.

* Classification of Renal tumors: I. Benign tumors: Cortical adenoma. Oncocytoma. II. Malignant tumors: Renal cell carcinoma. Wilms tumor.

Both benign and malignant tumors occur in the kidney. With the exception of oncocytoma, the benign tumors rarely cause clinical problems. Malignant tumors, on the other hand, are of great importance clinically and deserve considerable emphasis. By far the most common of these malignant tumors is renal cell carcinoma, followed by Wilms tumor, which is found in children

Renal cortical adenoma * Clinical Features: Usually an incidental finding. Often seen in patients receiving long-term hemodialysis, also more common in kidneys scarred from chronic pyelonephritis.

* Gross Pathology: The tumors are smaller than 5 mm. Soft, well-circumscribed mass with yellow to gray cut surface surrounded by compressed adjacent kidney parenchyma

On microscopic examination: They are composed of complex, branching, papillomatous structures. The cells may also grow as tubules, glands, cords, and sheets of cells. The cells are cuboidal to polygonal in shape and have regular, small central nuclei, scanty cytoplasm, and no atypia.

Renal adenoma

Renal oncocytoma * Clinical Features: Most are asymptomatic, although flank pain may be a presenting complaint; hematuria may be seen. Computed tomography or magnetic resonance imaging may identify central scar.

* Gross Pathology: Well-circumscribed, homogeneous cortical tumor Mahogany-brown cut surface. Often shows a central, irregular fibrous scar (in about 40% of cases). Bilateral or multicentric in 2% to 3% of cases

Renal oncocytoma

On microscopic examination: the tumor consists of large, eosinophilic cells having small, round, benign-appearing nuclei that have large nucleoli. The cells are arranged in nests separated by edematous and hyalinized fibrous stroma.

Renal oncocytoma

Renal cell carcinoma

* Epidemiology: Renal cell carcinomas represent about 1% to 3% of all visceral cancers and account for 85% of renal malignancy in adults. The tumors occur most often in older individuals, usually in the sixth and seventh decades of life, showing a male preponderance in the ratio of 3:1.

Because of their gross yellow color and the resemblance of the tumor cells to clear cells of the adrenal cortex, they were at one time called hypernephroma. It is now clear that all these tumors arise from tubular epithelium and are therefore renal adenocarcinomas. Most renal cancer is sporadic, but unusual forms of autosomal-dominant familial cancers occur, usually in younger individuals.

* Risk factors for RCC: Cigarette smoking is the most significant risk factor. Obesity (particularly in women). Hypertension. Unopposed estrogen therapy. Exposure to asbestos, petroleum products, and heavy metals. Acquired polycystic kidney disease secondary to dialysis

* Clinical presentation of RCC: Hematuria. Flank pain. Flank lump. This triad is seen in only 10% of cases. The most reliable of the three is hematuria, but it is usually intermittent and may be microscopic; thus, the tumor may remain silent until it attains a large size. At this time, it gives rise to generalized constitutional symptoms, such as fever, malaise, weakness, and weight loss.

This pattern of asymptomatic growth occurs in many patients, so the tumor may have reached a diameter of more than 10 cm when it is discovered. However, many of these tumors are being discovered in the asymptomatic state by incidental radiologic studies (e.g., computed tomographic scan or magnetic resonance imaging) usually performed for non-renal indications.

Renal cell carcinoma tends to produce a diversity of systemic symptoms not related to the kidney. In addition to the fever and constitutional symptoms mentioned earlier, renal cell carcinomas produce a number of paraneoplastic syndromes, ascribed to abnormal hormone production, including polycythemia, hypercalcemia, hypertension, hepatic dysfunction, feminization or masculinization, Cushing syndrome, eosinophilia, leukemoid reactions, and amyloidosis.

One of the common characteristics of this tumor is its tendency to metastasize widely before giving rise to any local symptoms or signs. In 25% of new patients with renal cell carcinoma, there is radiologic evidence of metastases at the time of presentation. The most common locations of metastasis are the lungs (more than 50%) and bones (33%), followed in order by the regional lymph nodes, liver and adrenals, and brain.

* Classification of Renal Cell Carcinoma: 1. Clear cell RCC. 2. Papillary RCC. 3. Chromophobe RCC. 4. Collecting duct carcinoma.

1. Clear cell RCC. This is the most common type, accounting for 70% to 80% of RCC. * Gross Pathology: Solitary renal cortical mass Bilaterality and multifocality more common in familial cases. Well-circumscribed, lobulated with golden-yellow cut surface. Cystic change, hemorrhage, necrosis, and calcification often present

* Histopathology: Nests of clear cells interspersed by delicate vascular network.

Robbins and Cotran’s: Pathologic Basis of Disease. Seventh edition. References: Robbins and Cotran’s: Pathologic Basis of Disease. Seventh edition.