A. Alport syndrome (hereditary nephritis) is a genetic defect involving the absence of type IV collagen. It results in renal failure and deafness because type IV collagen is an integral component of both the glomerular basal lamina and the tectorial membrane of the inner ear.
B. Diabetic nephropathy is characterized by nodular masses of mesangium (Kimmelstiel-Wilson masses) within the renal glomerulus and by hyaline thickening of the glomerular basal lamina.
C. Renal adenocarcinoma accounts for 90% of kidney cancers in adults.
1. Renal adenocarcinoma arises from renal tubular epithelium.
2. Diagnostic features include costovertebral pain, palpable masses, and hematuria. This tumor generally metastasizes widely (e.g., lung, bones) before any local symptoms or signs are present.
3. It is found in approximately 70% of patients with von Hippel-Lindau (VHL) syndrome (i.e., hemangioblastomas of the central nervous system and retina). VHL syndrome is due to a mutation of the VHL gene located on the short arm of chromosome 3 (3p) that codes for a tumor suppressor protein probably involved in signal transduction.
Figure 19-3. (A) Light micrograph of kidney cortex. A renal glomerulus (a capillary network) is shown along with the parietal layer of Bowman's capsule (arrow) and visceral layer of Bowman's capsule (podocytes; double arrows). PCT - proximal convoluted tubules. (IS) Light micrograph of kidney medulla. Cross-sections of various kidney tubules and vasa rectae are shown. CD = collecting duct; ST = proximal or distal straight tubule; t - descending of ascending thin loop of Henle; vr = vasa rectae.
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