CHAPTER 12
Urinary System
235
CLINICAL CORRELATIONS
Figure 12-12A.
Renal Oncocytoma
. H&E,
3
216
Renal oncocytoma
is a benign and less common neoplasm
of the kidney and originates from the epithelium of the
proximal tubules. It is typically a solid, encapsulated mass
with homogeneous enhancement in radiographic imaging.
Gross examination shows a spherical mass with a mahog-
any cut surface and a tan, fl
eshy central scar. Histologi-
cally, the tumor cells are large with abundant eosinophilic
cytoplasm due to the presence of numerous mitochondria.
The cells are arranged in sheets or in a tubulocystic pat-
tern. It is usually asymptomatic and detected as an inci-
dental renal mass on imaging. Treatment options include
surgical excision of the kidney (
nephrectomy
) or removal
of a portion of the kidney (partial nephrectomy).
Figure 12-12B.
Hemodialysis.
Hemodialysis
is a common treatment for end-stage kidney
disease. The
dialyzer
is a canister containing thousands of
small F
bers through which blood is passed. The F bers are
made up of semipermeable membranes with small pores
allowing wastes and extra fl
uids to pass from the blood
into a solution. A cleansing fl
uid called
dialysate
is pumped
around the F
bers. Solute and extra fl
uids are cleared from
the blood compartment by either diffusion or ultraF
ltra-
tion, depending on the concentration gradient and pres-
sure difference between the blood and the dialysate. The
cleansed blood is returned via the circuit back to the body.
Hemodialysis is usually given three times a week and can
be done in a dialysis center or at home. The model illus-
trated here is commonly used in critical care units.
Neoplastic
oncocytic
cells
A
Blood from patient
Blood back to patient
Dialyzer
B
SYNOPSIS 12-1
Clinical and Pathological Terms for the Urinary System
Glomerulonephritis
: Refers to primary glomerular disease not related to infection of the kidneys themselves. The causes of
glomerulonephritis are heterogeneous, such as viral or bacterial infection; drugs; and malignancy, resulting in many distinct
clinical entities including focal and segmental glomerulonephritis and membranous nephropathy. The causes are often not
identiF ed (idiopathic glomerulonephritis).
Glomerulopathy
: Refers to secondary glomerular injury as a result of systemic diseases, such as diabetes mellitus and
systemic lupus erythematosus.
Glomerulosclerosis
: Scarring or sclerosis of the renal glomeruli in diseases such as diabetic nephropathy and focal segmental
glomerulosclerosis.
Dysuria
: Pain or burning upon urination, most often caused by a urinary tract infection affecting the bladder (cystitis) or
urethra (urethritis).
Frequency
: The need to urinate more often than normal without an increase in total urine output; common causes include
lower urinary tract infection and benign prostatic hyperplasia; other less common causes include tumors and
extrinsic
bladder compression.
Hematuria
: The presence of blood in the urine, causes of which include trauma, infection, tumors of the urinary system,
kidney stones, and hyperplasia of the prostate gland; hematuria may be microscopic or “macroscopic,” meaning visible
to the unaided eye.
Lithotripsy
: Extracorporeal shock wave lithotripsy is a procedure for treating kidney and ureteral stones using focused
high-energy shock waves that pass through the body and break stones into small pieces that can then pass into the urine
and be eliminated.
Urgency
: A strong urge to urinate, most often caused by a lower urinary tract infection or other causes of bladder irritation
such as interstitial cystitis, which mainly affects females.
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