Assistant professor of pathology Renal tumors-1 Dr. Abdelaty Shawky Assistant professor of pathology

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

With the exception of oncocytoma, 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 that affects adults, 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 examination: The tumor is smaller than 5 mm. Soft, well-circumscribed mass with yellow to gray cut surface surrounded by compressed adjacent kidney parenchyma

* Microscopic examination: They are composed of papillomatous structures, tubules, and glands. The cells are cuboidal in shape and have small central nuclei, scanty cytoplasm, and no atypia.

Renal adenoma

Renal oncocytoma * Clinical Features: Most cases are asymptomatic, although flank pain may be a presenting complaint; hematuria may be seen. CT or MRI may identify a central scar.

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

Renal oncocytoma

On microscopic examination: the tumor consists of large, eosinophilic cells having small 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. Most renal cancer is sporadic, but unusual forms are a familial.

* 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.

Renal cell carcinoma tends to produce a diversity of systemic symptoms not related to the kidney termed paraneoplastic syndromes, ascribed to abnormal hormone production including; Polycythemia. Hypercalcemia. Hypertension.

Hepatic dysfunction. Feminization or masculinization. Cushing syndrome. Leukemoid reactions. 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 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.