Pathology-Renal & Urinary

Question 1

When performing a FAST exam on your fellow med student you are having difficulty finding his kidneys. Eventually you find them more centrally located in the abdomen. What congenital malformation would cause the kidneys to be located in this position?

Answer 1

Horseshoe kidneys stop ascending during fetal development because they get snagged on the inferior mesenteric artery.

Question 2

A mother brings her 2 year old boy in to see you complaining of constipation over the last week. Radiographs reveal an enlarged right kidney that is obstructing bowel and causing the child to be constipated. What congenital malformation may cause this radiographic finding?

Answer 2

Unilateral agenesis, in this case of the left kidney. The right kidney hypertrophies due to hyper filtration from trying to do the work of two kidneys.

Question 3

A pregnant mother comes to see you because she has not felt her baby kick for the past 3 days. She is 30 weeks along and very concerned. Physical exam reveals minimal amniotic fluid. You determine that the fetus is dead and help her in delivery. The child is seen below. Autopsy reveals underdeveloped lungs. Why did this child not survive?

Answer 3

This child has bilateral renal agenesis that causes oligohydramnios. The child’s symptoms are in line with the classic Potter sequence (flattened face, lowered ears, pulmonary hypoplasia and malformations of the extremities).

Question 4

A mother comes to your office for her 20 week pregnancy ultrasound. Visualization of the child reveals abnormal facies, shortened extremities and pulmonary hypoplasia. Both kidneys are there, however, cysts are observed bilaterally. There is no family history of cystic kidney disease on either side of the family. What would you expect to find in this neonate if you biopsied one of the cysts?

Answer 4

Dysplastic kidney disease characterized by abnormal tissue (cartilage as seen below) in the renal parenchyma. Dysplastic kidney disease is not inheritable.

Question 5

A mother brings her 14 year old girl in to see. She complains of bilateral flank pain and a headache. Physical exam reveals hypertension, a mid-systolic click on the cardiac exam and hematuria. Several family members have similar symptoms. What is most likely causing her symptoms?

Answer 5

Autosomal dominal PKD. This is a mutation in APKD1 or APKD2 that causes polycystin to build up and create cysts in the kidney. AD PKD is also associated with berry aneurisms (headache), hepatic cysts and mitral valve prolapse (murmur).

Question 6

A newborn baby is brought to your office due to jaundice, flattened facies, pulmonary hypoplasia and shortening of the extremities. Physical exam reveals a blood pressure of 120/80. what is your diagnosis?

Answer 6

Autosomal recessive PKD. This child is in renal failure. Bilateral cysts development in the kidneys makes them non-functional and causes newborns to present with oligohydramnios. Cysts also develop on the liver in this disease, causing hepatic fibrosis and jaundice.

Question 7

A mother brings her 8 year old boy in to see you complaining of hematuria. Urinalysis reveals proteinuria and physical exam reveals hypertension. The father had a similar condition when he was a child and needed double kidney transplantation. Ultrasonography reveals shrunken kidneys. Where are you most likely to find the pathology when getting a CT of this patient?

Answer 7

This is medullary cystic kidney disease. It presents with renal failure, parenchymal fibrosis and shrunken kidneys. You would find cysts in the medullary collecting ducts on CT.

Question 8

What are the hallmark presentations of acute renal failure?

Answer 8

Azotemia (increased nitrogenous waste like BUN) and oliguria (decreased urine production)

Question 9

In what ways can people develop acute renal failure?

Answer 9

Decreasing blood flow (pre-renal azotemia), decreasing outflow of urine (post-renal azotemia) and decreased function within the kidney (intrarenal azotemia)

Question 10

A 77 year old male comes to the ED due to increasing dyspnea over the past few days. He has a history of heart failure. He also complains of recent oliguria, confusion and dry mouth. Blood analysis reveals a BUN:Cr ratio of 25. What is your diagnosis and what is causing this patients blood work to manifest this way?

Answer 10

This patient has pre-renal azotemia from decreased blood flow to the glomerulus due to heart failure. The BUN:Cr ratio is elevated because the glomerulus senses decreased flow and sends out renin, which in turn causes secretion of aldosterone. Aldosterone acts on the nephron to resorb more water and Na+. Additional BUN gets resorbed in the process. This causes the BUN:Cr ratio in the blood to go up because Cr is still being filtered at a constant rate and cannot be resorbed.

Question 11

A 44 year old male presents to the ED in septic shock. Once he is stabilized you run some blood work to see how everything is going. You note the patient has an elevated BUN:Cr ratio in the blood. He also complains of oliguria. Further analysis reveals a decreased eGFR. What would you expect to see in analysis of renal tubular function in this patient?

Answer 11

This patient is presenting with acute pre renal azotemia (decreased eGFR, azotemia, oliguria and increased BUN:Cr). Since its pre-renal, you know his tubular function remains intact and his FENa (Fractional Excretion of Na+ indicates how well the tubules are able to resorb Na+) < 1% and urine osmolality > 500 (tubules have ability to concentrate the urine)

Question 12

A patient presents to the ED with excruciating flank pain. He also complains of oliguria and confusion. Renal ultrasound reveals a renal calculus in the right ureter. What lab values would you expect to see if you analyzed this patient’s BUN:Cr ratio in the blood, FENa and urine osmolality?

Answer 12

This is an acute post-renal azotemia. This presents with a BUN:Cr blood ratio > 15, a normal FENa < 1% and a normal urine osmolality > 500.

Question 13

A patient presents to the ED with excruciating flank pain. He also complains of oliguria and confusion. Renal ultrasound reveals a renal calculus in the right ureter. The doctor says the calculus should pass on its own and sends the patient home. What lab values would you expect to see if you analyzed this patient’s BUN:Cr ratio in the blood, FENa and urine osmolality a week later and the calculus was still blocking the ureter?

Answer 13

Long-standing post-renal obstruction leads to tubular epithelium damage. This results in decreased resorption of BUN and Na+. Lab values would reveal a decreased BUN:Cr blood ratio and an FENa > 2%. Additionally, renal tubular damage limits the kidney’s ability to concentrate urine and osmolality < 500.

Question 14

What is the most common cause of acute renal failure?

Answer 14

Acute Tubular Necrosis

Question 15

What change would you expect to see in the eGFR of the patient whose renal biopsy is shown below. What would you expect to see in his UA?

Answer 15

This is acute tubular necrosis. Note the anucleate epithelial cells that have sloughed from their basement membrane into the tubular lumen. This causes blockade of the tubule and decreases GFR due to back pressure. Clumping of the necrotic cells will manifest as brown granular casts excreted in the urine.

Question 16

What portions of the nephron are particularly susceptible to ischemic acute tubular necrosis?

Answer 16

The proximal tubule and medullary segment of the thick ascending limb do a lot of reabsorption and need a lot of energy. In the case of decreased pre-renal blood supply, these are typically the first cells to go.

Question 17

A patient presents to your clinic with a blood pressure of 100/60, when he is normally hypertensive. If further examination of this patient reveals nephrotoxic acute tubular necrosis, where is the most likely site of damage and what are the most likely agents?

Answer 17

The proximal tubule does most of the resorption and is most susceptible to nephrotoxic agents. These agents include aminoglycosides, heavy metals, myoglobinuria, ethylene glycol (antifreeze), radiocontrast dye and urate.

Question 18

A panicked parent brings his 2 year old son to the ED because he was stumbling around the house and lost consciousness for a couple of minutes. This has never happened before and happened suddenly. Urine analysis reveals oxalate crystals. What is the most likely cause of this child’s symptoms? What else would you expect to see in the child’s urine analysis and blood work?

Answer 18

Antifreeze (ethylene glycol) has a sweet taste and kids may mistake it for juice. It is nephrotoxic and causes acute tubular necrosis. Acute tubular necrosis presents with elevated BUN and creatinine levels (due to inability to create a GFR due to blockade). Patients also become hyperkalemic (due to decreased K+ excretion) and acidotic (due to increased anion gap from decreased excretion of organic anions).

Question 19

Why would you give a patient allopurinol prior to chemotherapy?

Answer 19

Chemotherapy causes rapid lysis of cancer cells. This results in a large release of uric acid that can damage the kidneys, causing acute tubular necrosis.

Question 20

Why do you need to put a patient on dialysis if they have acute tubular necrosis? How long might they be on dialysis for?

Answer 20

Electrolyte imbalances created by tubular necrosis can be fatal. The tubular cells are stable cells. This means they can re-enter the cell cycle and regenerate, but it takes 2-3 weeks. Oliguria may persist that long and continue the need for dialysis.

Question 21

A 67 year old man is admitted to the hospital for pneumonia. He has a history of heart failure and arthritis. He is given penicillin for the pneumonia and takes furosemide and ibuprofen regularly. He recovers within 2 days and is sent home and told to continue his antibiotics. A week later he develops a fever, rash and oliguria. Renal biopsy is shown below. What would you expect to see in this patient’s urine?

Answer 21

Note the tubules in the kidney look fine, but there is an inflammatory infiltrate in the interstitium. NSAIDs, penicillin and diuretics are the most common causes of acute interstitial nephritis. They induce a hypersensitivity reaction that causes inflammation of the renal interstitium and tubules. The common finding in the patient’s urine would be eosinophils.

Question 22

A 19 year old female comes to the ED complaining of hematuria and flank pain. History only reveals a broken vertebra for which she has been taking aspirin for the past month or so. What is likely causing her symptoms?

Answer 22

A drug-induced hypersensitivity reaction that causes acute interstitial nephritis. Continued damage can result in renal papillary necrosis, which is seen in this patient.

Question 23

What are the common causes of renal papillary necrosis?

Answer 23

Chronic analgesic abuse (aspirin/phenacetin), diabetes, sickle cell and severe acute pyelonephritis.

Question 24

What is the definition of nephrotic syndrome?

Answer 24

A glomerular disorder resulting in proteinuria > 3.5g/day

Question 25

Why do patients with nephrotic syndrome present with edema, increased infection, increased DVT and increased CAD?

Answer 25

Edema = hypoalbuminemia, Increased infection = hypogammaglobulinemia, DVT = excretion of anti-thrombin III, CAD = hyperlipidemia & hypercholesterolemia

Question 26

You are doing rounds in the oncology wards and see a 12 year old boy with Hodgkin lymphoma. Physical examination reveals edema and hypertension for his age. What is likely causing the symptoms in this child? How would you treat him?

Answer 26

MCD (Minimal Change Disease) is the most common cause of nephrotic syndrome in children. It is normally idiopathic but can also be associated with Hodgkin lymphoma due to Reed-Sternberg cells. These B cells secrete tons of cytokines that damage the podocytes in the glomerulus. These patients have an excellent response to steroids due to decreased production of cytokines.

Question 27

What are you likely to see on histological analysis of a patient's renal tissue who has MCD?

Answer 27

Normal H&E stain. Negative immunofluorescence. Effacement of podocyte foot processes on EM.

Question 28

Why do patients with MCD usually present with edema, but no increase in infections?

Answer 28

Selective proteinuria: loss of albumin but not of immunoglobulin.

Question 29

What is the most common type of nephrotic syndrome in Hispanics and African Americans? What conditions is this condition associated with?

Answer 29

Focal Segmental Glomerular Sclerosis (FSGS). Normally it is idiopathic, but can be associated with HIV, heroin use and sickle cell disease.

Question 30

A 32 year old African American male comes to see you. He has a history of HIV and heroin use. He also has sickle cell disease. He complains of recent edema in his face, arms and lower legs. He also says his blood pressure keeps going up. What would you expect to see on histological examination of this patient's kidney?

Answer 30

FSGS. H&E would reveal focal (only a few glomeruli) and segmental (only part of the glomeruli) sclerosis. EM would reveal effacement of the podocyte pedicels. Immunofluorescence would be negative.

Question 31

You suspect a patient has nephrotic syndrome due to minimal change disease. He has Hodgkin's lymphoma so your attending physician gives you the go-ahead to try steroid therapy. How will this patient's condition progress if he is not responsive to steroid therapy?

Answer 31

This means that he does not have MCD and will progress to FSGS and eventually to chronic renal failure.

Question 32

What is the most common cause of nephrotic syndrome in caucasian adults? What other conditions is this condition associated with?

Answer 32

Membranous nephropathy. It is usually idiopathic, but can be associated with Hep B, Hep C, solid tumors, SLE or drugs (NSAIDs & penicillamine)

Question 33

What is the most common disorder that presents in the kidneys of patients with lupus?

Answer 33

Diffuse proliferative glomerulonephritis

Question 34

A patient comes to see you complaining of high blood pressure, a couple of DVTs in the past year, peripheral edema and increased pulmonary infections. Physical exam only reveals a malar rash and history reveals UV sensitivity. What is most likely causing this patient's condition? What would you expect to see on histological examination of the patient's kidney?

Answer 34

When patients with lupus present with nephrotic syndrome it is usually membranous nephropathy. On H&E you would see thickening of the glomerular basement membrane, granular immune complex deposition on immunofluorescence and subepithelial deposits with a "spike and dome" appearance on EM (from collagen deposition on top of immune complex on basement membrane).

Question 35

A 45 year old male comes to see you complaining of increased peripheral edema, respiratory infections and DVTs in the past year. Physical exam reveals high blood pressure. PMH reveals hepatitis C. What may be causing this patient's nephrotic syndrome and what would you expect to see on histological examination of his kidneys?

Answer 35

Membranoproliferative glomerulonephritis. H&E will show thick capillary membranes with a "tram-track" appearance (from mesangial cell plasma membrane proliferation splitting the immune complex deposit in half). Granular immune complex deposition in the endothelium and basement membrane will be seen on immunofluorescence.

Question 36

What are the two different types of membranoproliferative glomerulonephritis? What conditions are they commonly associated with?

Answer 36

Type I = subendothelial immune complex deposits (associated with Hep B & Hep C). Type II = basement membrane immune complex deposits (C3 nephritic factor stabilizing C3 convertase)

Question 37

Which type of membranoproliferative glomerulonephritis is more often associated with the "tram-track" appearance?

Answer 37

Type I (subendothelial deposits).

Question 38

How do patients with C3 nephritic factor develop membranoproliferative glomerulonephritis?

Answer 38

C3 nephritic factor (an antibody) stabilizes C3 convertase. This is the enzyme that converts C3 to C3a & C3b. Stabilizing this enzyme results in over activation of complement, inflammation and damage to the glomerulus.

Question 39

What condition can result in nephrotic AND nephritic syndrome?

Answer 39

Membranoproliferative glomerulonephritis.

Question 40

Why should this patient be put on an ACE inhibitor?

Answer 40

Note the Kimmelsteil-Wilson nodule, pathopneumonic for diabetes. This starts with high blood sugar in diabetic patients results in NEG (non-enzymatic glycosylation) of vascular basement membrane which makes them leaky. This allows protein to leak out, causes hyaline thickening and arteriolosclerosis. This preferentially happens at the glomerular efferent arteriole. Arteriolosclerosis increases pressure in the glomerulus and causes hyperfiltration, microalbuminuria, mesangial sclerosis and nephrotic syndrome. This process can be slowed by inhibiting ACE, because angiotensin II vasoconstricts at the efferent glomerular arteriole.

Question 41

A 78 year old male comes to see you complaining of increased facial edema and blood pressure in the last month. Renal biopsy is shown below. What is causing this patient's condition?

Answer 41

Apple-green birefringence under polarized light after congo-red stain is diagnostic of systemic amyloidosis. Systemic amyloidosis most commonly affects the mesangium and causes nephrotic syndrome.

Question 42

What are the hallmark features of nephritic syndrome?

Answer 42

Glomerular inflammation & bleeding. Limited proteinuria (\<3.5g/day), oliguria, azotemia, salt retention, hypertension, periorbital edema and dysmorphic RBCs and RBC casts in the urine.

Question 43

What would you see on biopsy of the glomerulus in a patient with nephritic syndrome? Why?

Answer 43

You would see a hyper cellular, inflamed glomerulus. This is due to immune-complex deposition and activation of complement (including C5a) that recruits neutrophils.

Question 44

A 10 year old female presents to your clinic complaining of a two day history of hematuria and periorbital edema. She also feels fatigued and labs reveal proteinuria of 2g/day. Her blood pressure was 170/90. History reveals a recent skin infection (impetigo) and pharyngitis 2-3 weeks ago. What is likely causing this patient's condition? What would you expect to see on biopsy of this patient's kidney?

Answer 44

This patient has post-strep glomerular nephritis (PSGN). Group A strep carries the M protein and it nephritogenic. On H&E you would expect to see a hyper cellular and inflamed glomerulus. Granular immune complex deposition on immunofluorescence and sub epithelial "humps" on EM.

Question 45

A patient comes to see you complaining of a three day history of oliguria, periorbital edema and hypertension. History reveals a sore throat three weeks ago. EM of her kidney biopsy is shown below. How do you treat this patient?

Answer 45

Note the sub epithelial "humps" indicative of PSGN. The immune-complexes in this condition actually start being deposited subendothlially. They eventually get pushed up into the sub epithelial space where they form these humps. Finally they will get pushed out into the lumen and resolve on their own. Thus treatment is supportive therapy until they resolve.

Question 46

A 40 year old female presents with oliguria, periorbital edema, hypertension and generalized confusion. History reveals impetigo infection 3 weeks ago. Nothing is found in the ED in her kidneys and she is sent home with some Motrin. A few days later she begins to have increasing edema and hematuria. She also feels palpitations. What would you expect to see on renal biopsy of this patient?

Answer 46

This patient started out as having PSGN. However, in adults this may sometimes become rapidly progressive glomerular nephritis (RPGN) and cause renal failure. Biopsy would reveal crescents in Bowman's space on H&E composed of fibrin and macrophages.

Question 47

A 40 year old female presents with oliguria, periorbital edema, hypertension and generalized confusion. History reveals impetigo infection 3 weeks ago. Nothing is found in the ED in her kidneys and she is sent home with some Motrin. A few days later she begins to have increasing edema and hematuria. She also feels palpitations. Renal biopsy reveals crescents composed of fibrin & macrophages. How would you determine the etiology of this patient's condition?

Answer 47

Her condition is textbook RPGN (rapidly progressive glomerular nephritis). You determine the etiology by immunofluorescence. Linear immunofluorescence = Goodpasture syndrome (due to antibody binding to glomerular basement membrane). Granular immunofluorescence = PSGN or diffuse proliferative glomerulonephritis (antigen-antibody complex deposition, usually sub-endothelial). Negative immunofluorescence = ANCA test (positive for cANCA = Wegener granulomatosis. positive for pANCA = microscopic polyangiits or Churg-Strauss)

Question 48

A 20 year old male presents with hematuria, periorbital edema, hypertension, hemoptysis and generalized confusion. Biopsy of the kidney reveals crescents in Bowman's capsule and a linear antibody deposition on immunofluorescence. What is the most likely etiology of this patient's symptoms?

Answer 48

Anti-basement membrane antibody + renal problems + lung problems = Goodpasture syndrome.

Question 49

A 38 year old female presents with hematuria, periorbital edema, hypertension, and generalized confusion. He had a sore throat about 3 weeks ago. Biopsy of the kidney reveals crescents in Bowman's capsule and a granular antibody deposition on immunofluorescence. What is the most likely cause of this patient's condition? What if he had lupus?

Answer 49

The most common granular deposition of antibody in this case is PSGN. The most common cause of these symptoms in lupus patients is diffuse proliferative glomerulonephritis.

Question 50

A 20 year old male presents with hematuria, periorbital edema, hypertension, hemoptysis and generalized confusion. Biopsy of the kidney reveals crescents in Bowman's capsule and absence of antibody deposition (pauci-immune) on immunofluorescence. What is your next step in making a diagnosis for this patient?

Answer 50

An ANCA test. If the patient's serum antibodies bind adjacent to the nucleus of a neutrophil they have a p-ANCA-related problem (microscopic polyangiits or Churg-Strauss). If the patient's serum antibodies bind to the cytoplasm they have c-ANCA-related problem (Wegener's granulomatosis).

Question 51

A 20 year old male presents with hematuria, periorbital edema, hypertension, hemoptysis and generalized confusion. He also says he has a long history of sinus infections. Biopsy of the kidney reveals crescent shapes in Bowman's capsule and absence of antibody deposition on immunofluorescence. ANCA assay reveals c-ANCAs. What is causing this patient's condition?

Answer 51

Wegener granulomatosis. This condition affects the lungs, nasopharynx and the kidneys.

Question 52

A 20 year old male presents with hematuria, periorbital edema, hypertension and generalized confusion. Biopsy of the kidney reveals crescent shapes in Bowman's capsule and absence of antibody deposition on immunofluorescence. ANCA assay reveals p-ANCAs. What is causing this patient's condition?

Answer 52

A positive p-ANCA is either microscopic polyangiitis or Churg-Strauss. This patient most likely has microscopic polyangiitis. If he had Churg-Strauss you would also see eosinophilia, granulomatous inflammation and asthma.

Question 53

A 9 year old boy comes to see you in clinic with the flu. Additionally, he complains of hematuria. Urinalysis reveals RBC casts. This is the third time you have seen him for the same condition. What is the most likely cause of this patient's condition? What complications is this child at risk for?

Answer 53

This is IgA nephropathy, the most common cause of nephropathy worldwide. It is due to IgA immune complex deposition in the mesangium of the glomeruli after a mucosal infection such as the flu (IgA levels go up with mucosal infections). Continued IgA immune complex deposition can slowly progress to renal failure.

Question 54

A 24 year old male presents with hematuria and no other symptoms. Other members of his family have a similar condition. What is causing this patient's condition and what other factors commonly present with this condition?

Answer 54

Alport Syndrome. It is an X-linked type IV collagen defect. It results in thinning and splitting of the glomerular basement membrane. Other symptoms that may present are sensory hearing loss and ocular disturbances.

Question 55

How do patients with cystitis usually present?

Answer 55

Dysuria (pain w/urination), urinary frequency, urgency and suprapubic pain. Systemic signs are typically absent. They may also have a history of urinary stasis, sexual intercourse or catheterization.

Question 56

How do labs typically present in patients with cystitis?

Answer 56

Cloudy urine w/ \> 10 WBCs/hpf, positive leukocyte esterase (pyuria) and nitrites (bacteria convert nitrates to nitrites). Culture \> 100,000 colony forming units.

Question 57

What are the 5 most common causes of cystitis?

Answer 57

1) E. coli (80%) 2) Staph saprophyticus (young sexually active woman) 3) Klebsiella pneumoniae 4) Proteus mirabilis (alkaline urine w/ammonia scent) 5) Enterococcus faecalis

Question 58

A 44 year old female presents with dysuria, urinary urgency, frequency and suprapubic pain. Urinalysis reveals 15 WBCs/hpf and leukocyte esterase. Culture does not reveal any bacteria. What is most likely causing this patient's condition?

Answer 58

This patient has sterile pyuria. Pyuria (\>10 WBCs/hpf) w/ a negative culture suggests urethritis due to Chlamydia trachoma tis or Neisseria gonorrhoeae.

Question 59

A 35 year old female presents with a fever, urinary frequency, dysuria and flank pain. She recently had a UTI but did not complete her antibiotic therapy. What would you expect to see on urinalysis of this patient?

Answer 59

This patient likely has pyelonephritis. This condition is like cystitis but includes systemic symptoms and flank pain. Since the infection is ascending up the tubules of the kidney, WBCs will congregate in the tubules and form casts, which will be seen on UA. You will also see leukocytosis.

Question 60

What are the most common pathogens in pyelonephritis?

Answer 60

E. coli (90%), Klebsiella and Enterococcus.

Question 61

What puts you at risk for chronic pyelonephritis?

Answer 61

Multiple bouts of acute pyelonephritis that causes interstitial fibrosis and atrophy of the tubules. This can be a result of renal obstruction or vesicoureteral reflux.

Question 62

A patient dies from septic shock after bacteria spread to the blood because he had chronic pyelonephritis. What are you likely to observe in gross examination of the patient's kidneys?

Answer 62

Cortical scarring, blunted calyces. If the patient had vesicoureteral reflux scarring would be present at the upper and lower poles of the kidney.

Question 63

A patient comes to see you complaining of dysuria, urinary frequency, urgency suprapubic pain, fever and right flank pain. He has a history of multiple UTIs and is thought to have vesicoureteral reflux. Biopsy of the kidney is shown below. What are you likely to observe in a urinalysis of this patient?

Answer 63

Note the atrophic tubules with eosinophilic proteinaceous material…this is called thyroidization of the kidney that happens in patients with chronic pyelonephritis. Urinalysis may reveal waxy casts in the urine.

Question 64

What puts patients at risk for nephrolithiasis?

Answer 64

High solute concentration that causes the solute to precipitate or low urine volume that increases solute concentration and causes it to precipitate.

Question 65

A 33 year old male presents with colicky pain, hematuria and right flank pain. What is the most common cause of this patient's condition? How would you treat him? What GI disorder is it associated with?

Answer 65

The most common cause of kidney stones is idiopathic hypercalciuria that forms a calcium oxalate or calcium phosphate stone. You would treat him with hydrochlorothiazide (a Ca2+-sparing diuretic that keeps Ca2+ in the blood). This is also associated with Crohn's disease (increased resorption of oxalate can bind Ca2+ and form a stone).

Question 66

What must you exclude if you see a patient with a calcium oxalate stone in his urine?

Answer 66

Hypercalcemia in the blood.

Question 67

A 33 year old male presents with colicky pain, hematuria and right flank pain. History reveals multiple UTIs in the past year. It is determined that the patient must go to surgery. The gross image of the patients kidney is seen below. What most likely caused this condition and what do you see?

Answer 67

Note the "stag horn calculus" in the renal calyxes. This is an ammonium magnesium phosphate calculus that forms as a result of infection by a urease positive organism (Proteus vulgaris or Klebsiella). The alkaline urine formed by these organisms causes the stone to form.

Question 68

A 27 year old male presents with colicky pain, hematuria and right flank pain. Imaging does not reveal any calculi. What might you use to treat this patient?

Answer 68

Uric acid stones are not radiopaque and cannot be seen on imaging. These stones are treated with potassium bicarbonate to make the urine pH higher and allopurinol is given to patients with gout.

Question 69

What factors put you at higher risk for uric acid kidney stones?

Answer 69

Hot, arid climates. Low urine volume and acidic pH. Hyperuricemia from high cellular turnover (as seen in leukemia and myeloproliferative diseases)

Question 70

A 7 year old female presents with colicky pain, hematuria and left flank pain. Imaging reveals a stag horn calculus in the left kidney. What is likely causing her symptoms? How would you treat her?

Answer 70

In children with a stag horn calculus you think cystinuria. This is a rare condition where there is a defect in tubules that decreases reabsorption of cyteins. Cysteine piles up and forms a stone. You would treat this patient with alkalization of urine and hydration.

Question 71

A 77 year old male presents with nausea, anorexia, pericarditis, platelet dysfunction, encephalopathy and deposition of urea crystals in the skin. What are these symptoms indicative of and what are three most common causes of this condition?

Answer 71

Each of these symptoms are a result of uremia (increased nitrogenous waste in the blood from chronic renal failure). Diabetes, hypertension and glomerular disease are the top three causes of end-stage renal failure.

Question 72

What are the clinical features of patients entering end-stage renal failure?

Answer 72

Uremia, salt and water retention, hypertension, hyperkalemia, metabolic acidosis (anion gap), anemia (less erythropoietin production), hypocalcemia (decreased hydroxylation of vitamin D and hyperphosphatemia from decreased phosphate excretion and phosphate binds up Ca) and renal osteodystrophy.

Question 73

Where is erythropoietin secreted from?

Answer 73

Renal peritubular interstitial cells

Question 74

What happens to the bones of patients with chronic renal failure?

Answer 74

They are hypocalcemic due to decreased vitamin D hydroxylation and increased blood phosphate levels. This results in increased secretion of PTH and resorption of bone. Initially this causes osteitis fibrous cystica. Decreased Ca2+ levels then causes osteomalacia because ossification of osteoid is decreased. Finally, patients get osteoporosis because of metabolic acidosis being buffered by Ca2+ that is pulled off of the bone.

Question 75

Two patients are sitting in the dialysis clinic. One is in end-stage renal failure at age 40 and the other is a diabetic in end-stage renal failure at age 70. Both have cysts on their kidneys. How might their kidneys differ?

Answer 75

The patient who is 70 and on dialysis will have shrunken kidneys due to chronic renal failure, not genetic.

Question 76

What major complication are patients on renal dialysis at risk for?

Answer 76

Renal cell carcinoma in the shrunken, cystic kidney.

Question 77

What renal tumor shows increased frequency in patients with tuberous sclerosis?

Answer 77

Angiomyolipoma. It is a hamartoma comprised of blood vessels, smooth muscle and adipose tissue.

Question 78

What three presentations are hallmarks of a malignant epithelial tumor that arises from the kidney tubules? What other symptoms present with this condition?

Answer 78

Renal cell carcinoma: Hematuria, a palpable mass and flank pain. Patients may also present with fever, weight loss or paraneoplastic syndromes (EPO=polycythemia, renin=hypertension, PTHrP=hypercalcemia, ACTH=Cushing's)

Question 79

What rare left-sided anatomical manifestation may present in patients with renal cell carcinoma?

Answer 79

Left-sided varicocele. The tumor has a propensity to block the renal vein, which would block drainage of the spermatic vein and cause a varicocele.

Question 80

What would you expect to see on histological examination of the tumor seen in this patient's kidney?

Answer 80

Note the yellow tumor mass that is characteristic of renal cell carcinoma. The most common subtype of these tumors is the clear cell type seen below.

Question 81

What triggers renal cell carcinoma?

Answer 81

Sporadic (smokers) or hereditary (younger patients and bilateral) loss of VHL tumor suppressor gene. This results in increased IGF-1, which promotes growth, and HIF, which increases VEGF (angiogenesis) and PDGF (tumor growth).

Question 82

What autosomal dominant disorder puts people at risk for renal cell carcinoma? What other cancer are they at risk for?

Answer 82

Von Hippel-Lindau Disease = AD inactivation of the VHL gene. They have increased risk for hemangioblastoma of the cerebellum in addition to renal cell carcinoma.

Question 83

Where do renal cell carcinomas love to spread to?

Answer 83

Renal vein and retroperitoneal lymph nodes.

Question 84

A mother brings her child in due to hematuria and a large left-sided mass. Physical exam reveals hypertension. Radiographs reveal a left kidney mass. Biopsy of the mass is shown below. What is the most likely tumor?

Answer 84

Note the prevalence of blastema, indicating Wilms tumor. Wilms tumor is the most common malignant renal tumor in children. The tumor is comprised of blastema, primitive glomeruli and tubules, and stromal cells.

Question 85

When is Wilms tumor associated with a WT1 mutation?

Answer 85

Sydnromic cases: WAGR syndrome (Wilms tumor, Aniridia, Genital abnormalities, mental/motor Retardation), Beckwith-Wiedemann Syndrome (Wilms tumor, Neonatal hypoglycemia, Muscular hemihypertrophy, Organomegally especially in the tongue)

Question 86

What three cancers commonly originate in the lower urinary tract?

Answer 86

Urothelial carcinoma, squamous cell carcinoma and adenocarcinoma

Question 87

What is the most common type of lower urinary tract cancer?

Answer 87

Urothelial carcinoma. It can arise in the renal pelvis, ureter, bladder or urethra. It most often arises in the bladder.

Question 88

What are the risk factors for urothelial carcinoma?

Answer 88

Cigarette smoke (from polycyclic aromatic hydrocarbons and naphthylamine), azo dyes (hair dyes) and long-term cyclophosphamide and phenacetin exposure.

Question 89

A 67 year old female presents to your clinic with painless hematuria. She is a smoker and a hairdresser. Ultrasonography reveals a mass in the bladder. What are the two most common ways such a mass might arise?

Answer 89

Flat (flat uroepithelial stacks) and papillary (tumors develop with a fibrovascular core)

Question 90

How do papillary urothelial carcinomas progress?

Answer 90

They start as low grade tumors, then move to high grade tumors and then invade.

Question 91

How do flat uroepithelial carcinomas progress? What mutation is it associated with?

Answer 91

They start as high grade tumors, then they invade. It is associated with early p53 mutations.

Question 92

Why do patients with urothelial carcinomas often have multifocal recurring tumors?

Answer 92

Field defect. The entire urothelial surface has been hit with carcinogens over a long period of time and is all mutated.

Question 93

What are the risk factors for squamous cell carcinoma of the lower urinary tract?

Answer 93

Squamous cells are not normally in the lower urinary tract, so you must first have squamous cell metaplasia from the uroepithelium. This can happen with chronic cystitis, schistosoma hematobium or long-standing nephrolithiasis (chronic inflammation).

Question 94

A young middle eastern male presents to your clinic with painless hematuria. What parasite could be causing this patient's hematuria?

Answer 94

Schistosoma hematobium is typically seen in a young middle eastern male. Chronic inflammation from it embedding in the wall is what causes squamous cell carcinoma.

Question 95

A patient presents with a malignant proliferation of glands at the dome of the bladder. What is the most likely cause of this condition?

Answer 95

Adenocarcinoma from urachal remnant. The urachus has glandular tissue and the rest of the bladder does not.

Question 96

What are the main associations with adenocarcinoma of the lower urinary tract?

Answer 96

Urachal remnant, cystitis glandularis (metaplasia to columnar glandular cells from chronic cystis) and bladder exstrophy (congenital failure to form anterior abdominal and bladder walls)