This presentation provides an anatomical and pathological review of cystic kidney diseases, centered around the gross examination of a nephrectomy specimen exhibiting severe autosomal dominant polycystic kidney disease (ADPKD).
The video first establishes normal kidney anatomy, including the layers of the parenchyma and the correct order of urine flow from the renal papilla to the ureter. It then details the distinguishing gross features, genetics, and clinical associations of three common cystic pathologies: ADPKD, Autosomal Recessive Polycystic Kidney Disease (ARPKD), and Acquired Cystic Kidney Disease (ACKD). Key differences in associated renal cell carcinoma (RCC) subtypes are noted (Clear Cell RCC for ADPKD; ACKD-associated RCC for ACKD).
Finally, the presentation outlines the specific grossing protocol for these specimens, emphasizing the need for pre-cutting weight measurement, careful serial sectioning to detect potential malignancy (solid/thickened cyst walls), identification of vascular and ureteric margins, and proper submission of tissue sections for histopathological analysis.
Summarizing the Pathology Review and Grossing Protocol for Cystic Kidneys
0:35 Kidney Identification: The presented specimen is identified as a kidney, a retroperitoneal organ whose blood supply is via the renal artery and vein.
1:48 Internal Anatomy and Urine Flow: The correct path of urine flow is established as: Renal Papilla $\rightarrow$ Minor Calyx $\rightarrow$ Major Calyx $\rightarrow$ Renal Pelvis $\rightarrow$ Ureter. The Renal Pelvis drains urine, while the Renal Sinus is the fat surrounding it.
3:40 Three Main Diseases: The presentation focuses on Autosomal Dominant Polycystic Kidney Disease (ADPKD), Autosomal Recessive Polycystic Kidney Disease (ARPKD), and Acquired Cystic Kidney Disease (ACKD).
4:01 Autosomal Dominant Polycystic Kidney Disease (ADPKD): This hereditary disorder (PKD1/PKD2 mutations) is characterized by multiple, large, expanding cysts that eventually cause renal failure. The specimen shown weighs about 1.5 kg, significantly larger than a normal kidney (~160g).
6:18 ADPKD Associations: ADPKD is associated with hepatic cysts, mitral valve prolapse, and Berry aneurysms (a common cause of death). The most commonly associated malignancy is Clear Cell RCC.
7:16 Autosomal Recessive Polycystic Kidney Disease (ARPKD): This disorder features smaller, radially arranged cysts resulting in a sponge-like kidney appearance. It is due to the PKHD1 gene mutation and carries high early mortality, often due to pulmonary complications (e.g., pulmonary hypoplasia).
8:23 Acquired Cystic Kidney Disease (ACKD): Occurs in patients with end-stage renal disease on prolonged dialysis (risk up to 90% after 10 years). The kidneys are typically normal size or smaller.
10:21 ACKD Malignancy: ACKD patients are at increased risk for Acquired Cystic Disease-Associated RCC.
10:41 Grossing Step 1: Weight and Sectioning: The specimen must be weighed before making any cuts perpendicular to the hilum, as fluid loss from cysts changes the overall weight. Inking margins is usually not necessary unless malignancy is suspected.
12:30 Margin Identification: The ureter is identified by its star-shaped lumen and longitudinal ridges; the renal vein is larger with a thinner wall; the renal artery is smaller with a thicker wall.
14:34 Main Findings Documentation: Pathology must describe the cystic renal parenchyma, including cyst contents (e.g., serous fluid, gelatinous material, hemorrhage) and their size range.
15:41 Critical Examination Point: The cyst walls must be serially sectioned and carefully examined for any solid, thickened, or papillary areas, as these findings may represent incidental RCC.
16:57 Required Sections: Routine sampling includes vascular and ureteric margins (on fast), 3β4 sections of cystic parenchyma (including any suspicious thickened areas), and sections of the renal sinus/pelvis and any non-involved parenchyma.
18:41 Reporting Pertinent Negatives: The final gross description must include a statement confirming that the pathologist looked for but did not find distinct masses ("no distinct masses grossly identified").