Chronic tubulointerstitial nephritis:
o Drugs (eg, analgesics, lithium, cyclosporine, tacrolimus)1
o Heavy metals (eg, lead, cadmium, mercury)
Introduction o Obstructive uropathy, nephrolithiasis, reflux disease
o Immunologic diseases:
Lupus, Sjögren syndrome, primary
Παθησεις ΕΝΔΟΝΕΦΡΙΚΕΣ ΠΟΥ ΔΕΝ ΑΦΟΡΟΥΝ ΤΟ ΣΠΕΙΡΑΜΑ = glomerulopathies, sarcoidosis - A study by
ΔΙΑΜΕΣΟ ΣΩΛΗΝΑΡΙΑΚΕΣ Maripuri et al found that out of 24 patients with
primary Sjögren syndrome who also had renal
ΣΑΦΩΣ ΣΥΧΝΑ ΣΥΝΥΠΑΡΧΕΙ ΑΡΧΟΜΕΝΗ ΣΠΕΙΡΑΜΑΤΙΚΗ ΒΛΑΒΗ ΣΕ impairment, biopsies revealed that 17 individuals
ΕΔΑΦΟΣ ΕΓΚΑΤΕΣΤΗΜΕΝΗΣ ΔΙΑΜΕΣΟΣΩΛΗΝΑΡΙΑΚΗΣ ΝΟΣΟΥ ΟΠΟΥ had tubulointerstitial nephritis as the primary
ΚΥΡΙΑΡΧΟΥΝ ΟΙ ΕΚΔΗΛΩΣΕΙΣ ΤΗΣ ΣΠΕΙΡΑΜΑΤΙΚΗΣ ΝΟΣΟΥ lesion behind their kidney dysfunction.2 Eleven of
the 17 patients had the chronic form of this
nephritis. The results, according to the
investigators, support the notion that in patients
ΤΑ ΑΙΤΙΑ ΚΑΙ Η ΠΑΘΟΦΥΣΙΟΛΟΓΙΚΟΙ ΜΗΧΑΝΙΣΜΟΙ ΤΗΣ with primary Sjögren syndrome, chronic
ΔΙΑΜΕΣΗΣ / ΣΩΛΗΝΑΡΙΑΚΗΣ ΝΟΣΟΥ ΠΟΙΚΙΛΛΟΥΝ, Ο ΔΕ ΑΣΘΕΝΗΣ tubulointerstitial nephritis is the most frequent
cause of renal impairment found through kidney
ΔΥΝΑΤΟ ΝΑ ΠΑΡΟΥΣΙΑΖΕΙ ΟΞΕΙΕΣ ΕΙΤΕ ΧΡΟΝΙΕΣ ΠΑΘΟΛΟΓΙΚΕΣ
Vasculitis, antineutrophil cytoplasmic antibody
(ANCA)–associated vasculitides, Wegener
ΕΚΘΕΣΗ ΣΕ ΦΑΡΜΑΚΑ – ΛΟΙΠΟΥΣ ΤΟΞΙΚΟΥΣ ΠΑΡΑΓΟΝΤΕΣ – ΒΑΡΕΑ granulomatosis
ΜΕΤΑΛΛΑ – ΣΠΑΝΙΩΣ ΣΥΣΧΕΤΙΣΗ ΜΕ ΛΟΙΜΩΞΗ Chronic transplant nephropathy
Η ΠΛΕΟΝ ΤΥΠΙΚΗ ΕΙΚΟΝΑ ΕΞΟΡΜΑΤΑΙ ΑΠΟ ΑΝΟΣΟΛΙΓΙΚΗ
o Neoplasia (eg, myeloma, leukemia, amyloidosis)
ΦΛΕΓΜΟΝΗ o Atherosclerotic kidney disease (ischemic) - Cholesterol
o Metabolic diseases (eg, hypercalcemia, cystinosis, potassium
depletion, nephropathy, hyperoxaluria)
o Genetics (eg, Alport syndrome, medullary cystic disease)
o Miscellaneous (eg, Balkan endemic nephropathy, Chinese
Tubulointerstitial diseases herb/aristolochic acid nephropathy)3,4
Acute tubulointerstitial nephritis: Pathophysiology
o Hypersensitivity reactions (eg, drugs, penicillins, sulfa drugs, ΣΕ ΔΟΜΙΚΟ ΕΠΙΠΕΔΟ Η ΑΝΑΜΕΝΟΜΕΝΗ ΕΙΚΟΝΑ ΣΕ ΟΞΕΙΑ
nonsteroidal anti-inflammatory drugs [NSAIDs] most common) ΑΛΛΑ ΚΑΙ ΣΕ ΧΡΟΝΙΟ ΔΙΑΜΕΣΗ ΝΕΦΡΟΠΑΘΕΙΑ ΕΙΝΑΙ ΤΟ
o Immunologic diseases (eg, associated with lupus, Goodpasture ΑΠΟΤΕΛΕΣΜΑ ΤΗΣ ΑΛΛΗΛΕΠΙΔΡΑΣΗΣ ΤΩΝ ΝΕΦΡΙΚΩΝ ΚΥΤΤΑΡΩΝ ΜΕ
syndrome) ΤΑ ΚΥΤΤΑΡΑ ΤΗΣ ΦΛΕΓΜΟΝΗΣ ΚΑΙ ΤΑ ΠΑΡΑΓΩΓΑ ΑΥΤΩΝ
o Acute transplant rejection
o Infections: Η ΚΥΤΤΑΡΙΚΗ ΚΑΤΑΣΤΡΟΦΗ ΣΥΝΕΠΑΓΕΤΑΙ ΤΗΝ ΠΑΡΟΥΣΙΑ
ΑΝΤΙΓΟΝΩΝ ΣΕ ΤΟΠΙΚΟ ΕΠΙΠΕΔΟ, ΔΙΗΘΗΣ ΜΕ ΚΥΤΤΑΡΑ ΦΛΕΓΜΟΝΗΣ,
Bacterial (must be accompanied by obstruction or ΕΝΕΡΓΟΠΟΙΗΣΗ ΠΡΟΦΛΕΓΜΟΝΟΔΩΝ ΚΑΙ ΧΗΜΕΙΟΤΑΚΤΙΚΩΝ
reflux) ΚΥΤΤΟΚΙΝΩΝ ΜΕ ΤΕΛΙΚΗ ΕΚΒΑΣΗ ΟΧΕΙΑ ΕΙΤΕ ΧΡΟΝΙΟ ΝΕΦΡΙΤΙΔΑ
Viral (eg, cytomegalovirus [CMV], hantavirus, HIV,
hepatitis B) These cytokines are produced by
Fungal (eg, histoplasmosis) inflammatory cells (ie, macrophages, lymphocytes)
Parasitic (eg, Leishmania, Toxoplasma) and also by the renal cells (ie, proximal tubule,
vascular endothelial cells, interstitial cells,
ΟΞΕΙΑ ΔΙΑΜΕΣΟΣ ΝΕΦΡΙΤΙΔΑ = ΣΩΛΗΝΑΡΙΑΚΗ ΚΑΤΑΣΤΡΟΦΗ /
ΔΥΣΛΕΙΤΟΥΡΓΙΑ ΜΕ / ΑΝΕΥ ΝΕΦΡΙΚΗ ΑΝΕΠΑΡΚΕΙΑ
ΑΝΕΞΑΡΤΗΤΑ ΑΠΟ ΤΗΝ ΕΚΤΑΣΗ ΤΗΣ ΣΩΛΗΝΑΡΙΚΑΗΣ
ΚΑΤΑΣΤΡΟΦΗΣ, Η ΝΕΦΡΙΚΗ ΔΥΣΛΕΙΤΟΥΡΓΙΑ ΚΑΤΑ ΚΑΝΟΝΑ
ΒΕΛΤΙΩΝΕΤΑΙ / ΑΝΑΣΤΡΕΦΕΤΑΙ, ΑΝΤΑΝΑΚΛΩΝΤΑΣ ΤΗΝ
ΑΝΑΓΓΕΝΗΤΙΚΗ ΙΚΑΝΟΤΗΤΑ ΤΩΝ ΣΩΛΗΝΑΡΙΩΝ ΜΕ ΑΝΕΠΑΦΗ ΒΑΣΙΚΗ
ΑΝΤΙΣΤΡΟΦΩΣ, Η ΧΡΟΝΙΟΣ ΔΙΑΜΕΣΗ ΝΕΦΡΙΤΙΔΑ ΧΑΡΑΚΤΗΡΙΖΕΤΑΙ United States
Primary tubulointerstitial diseases, ie, diseases of the renal
tubules and interstitium sparing the glomeruli, constitute 10-15% of
o ΣΩΛΗΝΑΡΙΑΚΗ ΑΤΡΟΦΙΑ all kidney diseases both in the United States and around
ΜΕ ΠΡΟΟΔΕΥΤΙΚΗ ΕΞΕΛΙΞΗ ΣΕ ΧΝΑ
In certain regions, such as the Balkans (ie, Yugoslavia, Bosnia,
ΜΗΧΑΝΙΣΜΟΙ ΟΞΕΙΑΣ ΔΙΑΜΕΣΗΣ ΝΕΦΡΙΤΙΔΑΣ : Croatia, Romania, Bulgaria), where endemic nephropathy is common,
interstitial diseases may be more prevalent.3,4
1..ΑΝΤΙΔΡΑΣΗ ΥΠΕΡΕΥΑΙΣΘΗΣΙΑΣ ΣΕ ΦΑΡΜΑΚΑ
o Tubulointerstitial disease may progress to end-stage renal
ΠΕΝΙΚΙΛΛΙΝΗ – ΦΣΑΦ – sulfa drugs disease.
o An increased incidence of uroepithelial cancers is found among
patients with analgesic nephropathy, aristolochic acid
nephropathy, and Balkan endemic nephropathy.3,4
2..ΟΞΕΙΑ ΣΩΛΗΝΑΡΙΑΚΗ ΝΕΚΡΩΣΗ
Neither acute nor chronic tubulointerstitial diseases
ΑΠΟΦΡΑΞΗ ‘Η ΠΑΛΙΝΔΡΟΜΗΣΗ + ΛΟΙΜΩΞΗ
of the kidney demonstrate racial predilections. Lead
nephropathy may be more common in black people because
of socioeconomic factors.
The kidney is remarkably resistant to
structural damage in bacterial infections, and, in
the absence of obstruction, damage from bacterial
infection in the kidney parenchyma is extremely
unlikely to occur. Analgesic nephropathy is 5-6 times more common in
women. This is generally attributed to women taking more
Studies have revealed transforming growth analgesics than men. However, a greater sensitivity to the toxic
factor beta (TGF β) as a major participant in effects of analgesics or differences in analgesic metabolism in
fibrogenesis. TGF β favors accumulation of collagen women cannot be ruled out.
and noncollagen basement membrane components
by direct stimulation of production and by Age
inhibiting matrix degradation enzymes such as
collagenases and metalloproteinases. All toxic nephropathies are related to the cumulative
effects of toxic substances, particularly lead, and consequently
Activation of nuclear transcription factors, are likely to be observed more frequently with advancing age.
such as nuclear factor kappa B (NF-B) in injured
kidney cells, with consequent transcription and However, this is highly variable.
release of proinflammatory cytokines into the
interstitium, appears to be a major mechanism of
chronic tubulointerstitial inflammation For example, people with severe lead poisoning during
accompanying proteinuric kidney diseases. childhood may present with chronic tubulointerstitial nephritis
in early adult life.
Atherosclerotic and/or ischemic kidney disease is increasingly
more common in elderly individuals.
Metabolic disorders, such as cystinosis, oxalosis, and
hypercalcemia, can occur in younger individuals.
Η ΑΜΕΣΗ ΔΙΑΚΟΠΗ ΤΟΥ ΤΟΞΙΟΥ ΠΑΡΑΓΟΝΤΑ, ΣΥΝΗΘΩΣ
ΑΛΛΑ ΟΧΙ ΠΑΝΤΟΤΕ ΣΥΝΕΠΑΓΕΤΑΙ ΤΗΝ ΥΠΟΣΤΡΟΦΗ ΤΗΣ ΝΟΣΟΥ,
ΚΑΠΟΤΕ Η ΝΟΣΟΣ ΕΠΙΜΕΝΕΙ ΕΒΔΟΜΑΔΕΣ ΠΡΙΝ ΤΗΝ ΕΝΑΡΞΗ
History depends on whether the tubulointerstitial nephritis is acute or Although any drug can potentially cause a
chronic. hypersensitivity reaction involving the kidney, the
following are the most frequently implicated:
Acute tubulointerstitial nephritis (general features)
o Antibiotics (eg, penicillins, cephalosporins, sulfa drugs,
ΤΥΠΙΚΗ ΕΝΑΡΞΗ = ΤΑΧΕΙΑ ΕΓΚΑΤΑΣΤΑΣΗ ΟΝΑ quinolones)
ΚΑΤΑ ΚΑΝΟΝΑ ΕΝΤΟΣ ΗΜΕΡΩΝ ΑΠΟ ΤΗΝ ΕΝΑΡΞΗ ΕΚΘΕΣΗΣ ΣΤΟ o Diuretics (eg, thiazides, furosemide)
ΤΟΞΙΚΟ ΠΑΡΑΓΟΝΤΑ o Allopurinol
o Interferon alfa
o Proton pump inhibitors
ΜΣΑΦ : ΜΕΤΑ ΑΠΟ ΕΚΘΕΣΗ ΜΗΝΩΝ
Acute tubulointerstitial nephritis
o ΑΥΞΗΣΗ ΤΩΝ IgE caused by NSAIDs
ΕΞΑΙΡΕΣΗ = rifampin, ΜΣΑΦ This condition is more common in elderly people,
perhaps because of the higher incidence of arthritic disorders in this
Acute allergic interstitial nephritis should not be
confused with the acute vasomotor renal insufficiency that can occur
ΗΠΙΑ ΔΙΑΜΕΣΗ ΝΕΦΡΙΤΙΔΑ in patients with preexisting underperfusion of the kidney.
ΕΝΙΟΤΕ = ΕΞΑΝΘΗΜΑ + ΑΙΜΑΤΟΥΡΙΑ A unique feature of allergic interstitial nephritis
caused by NSAIDs is that patients may present with nephrotic
ΥΠΟΥΛΗ ΕΓΚΑΤΑΣΤΑΣΗ ΣΩΛΗΝΑΡΙΑΚΗΣ ΔΙΑΤΑΡΑΧΗΣ syndrome. In such patients, massive proteinuria with
hypoalbuminemia and edema are present in addition to the typical
= [Fanconi syndrome : ΑΜΙΝΟΞΥΟΥΡΙΑ – ΓΛΥΚΟΖΟΥΡΙΑ – features of acute interstitial nephritis.
ΝΕΦΡΟΣΩΛΗΝΑΡΙΑΚΗ ΟΞΕΩΣΗ ]
Findings on kidney biopsy
ΠΡΩΤΕΙΝΟΥΡΙΑ = ΑΠΟΥΣΙΑΖΕΙ Ή ΕΙΝΑΙ ΗΠΙΑ show features of minimal
o ΟΥΡΙΝΑΛΥΣΗ = change nephrosis in addition
to the characteristic findings
o ΜΙΚΡΟΣΚΟΠΙΚΗ ΑΙΜΑΤΟΥΡΙΑΣΤΕΙΡΑ ΠΥΟΥΡΙΑ
o ΜΕ / ΑΝΕΥ ΕΩΣΙΝΟΦΙΛΑ
ΑΝ ΚΑΙ Η ΚΛΙΝΙΚΗ ΕΙΚΟΝΑ ΕΙΝΑΙ ΤΥΠΙΚΗ ΚΑΤΑ ΚΑΝΟΝΑ ΔΙΑΓΝΩΣΗ of interstitial nephritis
ΤΙΘΕΤΑΙ ΜΟΝΟ ΜΕΤΑ ΑΠΟ ΒΙΟΨΙΑ
ΜΣΑΦ ΤΟΞΙΚΟΤΗΤΑ = ΒΑΡΕΙΑ ΠΡΩΤΕΙΝΟΥΡΙΑ, ΣΥΧΝΑ ΔΙΚΗΝ
Acute tubulointerstitial nephritis
Antibiotic-induced acute tubulointerstitial
caused by miscellaneous agents
Infections with viral agents, bacteria, and fungi
This form of nephritis is usually observed in the are occasionally associated with acute interstitial
hospital setting during treatment of serious infections, within nephritis. Hantavirus, CMV, and HIV are common among the
several days to weeks of initiation of antibiotic therapy. infectious agents associated with acute interstitial nephritis.
Rash, eosinophilia, and eosinophiluria, as well as pyuria (sterile),
In HIV disease, acute interstitial nephritis is usually
hematuria, and modest proteinuria (usually 1 g/d), are common.
observed in conjunction with glomerular disease (ie, focal
Unlike in NSAID-induced allergic interstitial nephritis, nephrotic range
proteinuria is very rare.
Parenchymal invasion by the virus is not always
If a renal biopsy is performed, eosinophils can be a component of the present, and other characteristic features, such as eosinophilia
interstitial nephritis and fever, are usually absent.
Occasionally, ill-defined granulomas are present Bacterial infection with renal parenchymal
invasion is sometimes responsible for acute interstitial
nephritis, but this is exceedingly rare in the absence of
Other infections such as tuberculosis and
histoplasmosis are also among the rare causes of acute
tubulointerstitial nephritis and may be diagnostic challenges.
Among antibiotics, rifampin is unique in that
the interstitial nephritis generally occurs when
the antibiotic is reintroduced after an interval.
Chronic tubulointerstitial nephritis
Furthermore, the interstitial nephritis associated with it
does not manifest with eosinophilia. (general features)
In some cases, rifampin-associated interstitial nephritis has The chronic form is an insidious disease and most probably
been reported to show casts containing immunoglobulin light represents the common final response pattern of the kidney to a
chains in tubular lumens without any evidence of myeloma in variety of insults and agents
Important causes include analgesics; lead; drugs, including
Flulike symptoms, flank pain, hypertension, and cyclosporine, cisplatin, and lithium; and metabolic disorders, notably
hypercalcemia, potassium depletion, and hyperoxaluria.
oliguric acute renal failure are common.
In some patients, circulating antirifampin antibodies and
immunoglobulin G (IgG) deposits along the tubular basement
Because of its insidious nature, chronic tubulointerstitial
membranes have been reported.
nephritis is often diagnosed incidentally on routine laboratory
screening or evaluation of hypertension.
Patients are usually asymptomatic. Hypertension is common
but not universal, and it is conspicuously absent in Balkan endemic
Clinical investigations may show modest elevation in
serum creatinine, evidence of tubular dysfunction (ie, renal
tubular acidosis), or Fanconi syndrome (ie, aminoaciduria,
glycosuria, hypophosphatemia, hypouricemia). Proteinuria is
usually mild, often less than 1 g/d.
In contrast to glomerular disease, a significant In some patients, a history can be elicited
fraction of the protein is low molecular weight (eg, of episodes of :
immunoglobulin light chains, beta2 microglobulin,
lysozyme, peptide hormones). o papillary necrosis, ie,
o gross hematuria with
These proteins are normally taken o flank pain occasionally accompanied by
up by the proximal tubules and o obstruction and
broken down there. Thus, in
diseases predominantly involving Clinically, patients with analgesic nephropathy
present with renal insufficiency, modest proteinuria, sterile
tubular structures, decreased pyuria, and anemia. Diagnosis can be supported by history
endocytosis of filtered proteins of heavy analgesic use, and computer-assisted
tomograms may reveal microcalcifications at the
leads to the characteristic tubular papillary tips.
Treatment is supportive and includes
Findings on kidney biopsy in chronic discontinuation of analgesic use. Long-term
tubulointerstitial nephritis usually show varying degrees follow-up studies have shown progression to
of interstitial fibrosis, tubular atrophy, arteriolar
sclerosis, and, occasionally, mononuclear cell infiltration
end-stage renal disease requiring dialysis, and
(see image below). increased incidence of uroepithelial cancers is
also observed in patients with analgesic
Often, the findings are nonspecific and the nephropathy.
etiology is not discernible from the biopsy; some diseases,
such as sarcoidosis, show noncaseating granulomas, and,
in viral diseases, immunostaining can yield clues to the
In patients with suspected lead exposure, an Lithium nephropathy
ethylenediaminetetraacetic acid (EDTA) lead
mobilization test or determination of tibial bone lead by Distal tubular dysfunction ie,
radiographic fluorescence can confirm lead etiology.
o concentrating defect,
o down-regulation of aquaporin-2
Analgesic nephropathy1 occurs in up to 50% of patients receiving lithium.
Analgesic nephropathy is the most common category
of chronic interstitial nephritis worldwide. This disorder occurs Chronic interstitial nephritis occurs in a small subset of patients
with long-term ingestion of combinations of receiving long-term lithium therapy who have had repeated
phenacetin, aspirin, and caffeine or phenacetin- episodes of lithium toxicity with high serum levels.
acetaminophen or NSAIDs and acetaminophen. In its
most severe form, it is associated with papillary necrosis.
The amount of phenacetin-acetaminophen
combination required to cause chronic interstitial nephritis has
been estimated to be at least 2-3 kg over many years.
Although initially thought to be exclusively associated
with phenacetin-containing combinations, all analgesics,
including acetaminophen, aspirin, and NSAIDs, can cause
analgesic-induced chronic tubulointerstitial nephritis.
Analgesic nephropathy is most common in
women in the sixth and seventh decades of life who have a
history of low back pain, migraine headaches, or other chronic
Cyclosporine- and tacrolimus-induced Lead nephropathy
Since antiquity, lead has been known to cause kidney
These agents, although indispensable in the disease and gout. In the modern industrialized world, lead
is a ubiquitous environmental and occupational toxin and is
management of solid organ transplantation, can an important cause of chronic tubulointerstitial nephritis and
cause acute and chronic nephrotoxicity. hypertension, mainly in urban poor communities and
particularly among black people.
The mechanism appears to be dependent largely on the
potent vasoconstrictive effects of these drugs. Chronic Children with severe lead poisoning can present
tubulointerstitial nephritis induced by cyclosporine or with encephalopathy and acute renal failure with
tacrolimus is common among patients receiving kidney, heart, Fanconi syndrome. Because lead has a biologic half-life of
liver, and pancreas transplants. several decades, if untreated by chelation, both intermittent
acute poisoning and low-level environmental exposure result
in chronic cumulative lead poisoning. The major
However, it is rare in bone marrow transplant recipients consequence of chronic lead poisoning is chronic
because they receive the drugs for a short time and generally at tubulointerstitial disease, usually in the third to fourth
lower doses. decades of life.
In renal transplant recipients, cyclosporine- or tacrolimus- A common source of lead poisoning is leaded paint
induced chronic interstitial nephritis is similar to chronic chipping in old urban tenements. Young children
rejection. attracted to the sweet taste of the leaded paint may ingest or
inhale dust particles containing lead and are at particular
Because the pathophysiology of both is poorly risk. In the industrial setting, welders, smelters, battery
understood, these conditions tend to be included under workers, painters, and restorers of old buildings, especially
in poorly ventilated work environments, can be exposed to
the generic term of chronic transplant nephropathy. toxic amounts of lead.
Most kidney transplant patients have a stable course with mild Hypertension is almost always present, and, in the
impairment of renal function. However, up to 10% of heart absence of appropriate testing or careful exposure history,
transplant recipients develop progressive renal insufficiency lead nephropathy is often misdiagnosed as so-called
and eventually require dialysis. hypertensive kidney disease. Patients with lead nephropathy
tend to have disproportionately worse hyperuricemia
compared to patients with other kidney diseases because of
the unique effects of lead on urate metabolism, and,
Both cyclosporine and tacrolimus frequently cause consequently, gout is common.
hypertension and hyperkalemia.
In retrospect, after careful investigation including the EDTA
lead mobilization test, many patients presumed to have
Hypomagnesemia caused by renal magnesium wasting is either gouty nephropathy or hypertensive
also common in cyclosporine-treated patients. nephrosclerosis are discovered to have lead
nephropathy. Identification of the lead etiology in patients
Concomitant use of calcium channel blockers presumed to have gout nephropathy has cast doubt on the
reduces nephrotoxicity. existence of this entity.
Long-term use of cyclosporine has been associated with patchy
interstitial fibrosis, usually in a striped pattern and with tubular
Thrombotic microangiopathy might further contribute to
both acute and chronic nephrotoxicity.
Obstructive uropathy Atherosclerotic kidney disease
Obstruction of urinary outflow as observed in : As life expectancy increases, atherosclerotic disease of the
kidney is emerging as a major category of chronic
o prostate disease, tubulointerstitial nephropathy.
o stone disease,
o neoplasm, and Unfortunately, no unanimity on nomenclature exists among
o retroperitoneal fibrosis experts, and kidney disease in this category is variably termed is :
among others, can cause chronic tubulointerstitial disease. o Ιchemic nephropathy,
o renovascular disease, and
Modest proteinuria and hyperkalemic renal tubular acidosis are o nephrosclerosis
Vesicoureteral reflux disease, usually congenital,
characteristically results in focal glomerulosclerosis In all likelihood, cases of so-called hypertensive
with nephrotic syndrome and a prominent kidney disease or hypertensive nephrosclerosis
tubulointerstitial component in adult life even if the belong in the category of atherosclerotic kidney
reflux has been corrected early. disease.
Superimposed infection and pyelonephritis often complicate Lack of appropriate diagnosis can explain the discrepancy in
obstruction. the incidence of kidney disease in hypertensive populations in
Europe and the United States.
Recurrent urinary tract infection itself can cause ammonium
magnesium phosphate stones, further aggravating In Europe, kidney disease is found in only about 1% of
tubulointerstitial disease and perpetuating infection. hypertensive populations, while in the United States 30% of all
end-stage disease requiring dialysis is attributed to hypertensive
Similarly, papillary necrosis and infection may complicate the kidney disease.
course and may lead to acute pyelonephritis with fever, flank
pain, hematuria, and, especially in elderly patients, urosepsis.
Atherosclerotic kidney disease is typically observed in
elderly white males who smoke, but it is by no means
confined to this population.
Many individuals with dyslipidemia and other
atherosclerotic phenomena, such as coronary artery disease,
carotid artery disease, and peripheral arterial disease, are prone
to involvement of renal arteries, regardless of age.
Often, these patients have hypertension, not necessarily
severe, with elevated serum creatinine and urea nitrogen
and proteinuria, 1-2 g/d. The course of progression of the
kidney disease is usually slower than in patients with glomerular
diseases such as diabetic nephropathy.
Diagnosis can usually be made clinically, and radiologic
investigations, such as duplex scanning of the renal arteries,
digital subtraction angiography, or magnetic resonance
imaging, reveal atherosclerotic stenosis of the renal arteries.
Kidney biopsy is seldom necessary and, if performed,
shows nonspecific changes of chronic tubulointerstitial
nephritis, ie, tubular atrophy, fibrosis, and arterial or arteriolar
sclerosis with paucity of cellular infiltration.
Because these patients tend to have atherosclerotic
complications, they are likely to experience multiple contrast
procedures and hence are at risk for acute recurrent contrast
nephropathy, which can accelerate progression to end-stage Metabolic disorders and
renal disease. nephropathy
No specific therapy is available, but good control of o Hypercalcemia,
hypertension, cessation of smoking, and vigorous control of o chronic potassium depletion, and
dyslipidemia with diet and with hepatic 3-methylglutaryl o cystinosis
coenzyme A (HMG-CoA) reductase inhibitors are expected to
result in improved outcomes.
can lead to chronic tubulointerstitial nephritis.
Hypercalcemia is the most common cause.
Cholesterol microembolic disease and
Chronic hypercalcemia can occur in :
This is a unique syndrome that has been recognized in the
setting of catheter procedures involving vasculature above the o primary hyperparathyroidism,
renal arteries, such as coronary angiography, although it can o sarcoidosis,
o multiple myeloma, and
occur in patients on anticoagulation; it can even
o other neoplasms (particularly with bone metastases) and
in vitamin D intoxication.
The pathophysiology is destabilization of atheroma plaques,
Even transient hypercalcemia can lead to chronic renal
either during catheter manipulation or spontaneously, resulting
in showering of cholesterol crystals downstream and eventual insufficiency; renal involvement is mostly confined to the
lodging of needle-shaped cholesterol crystals in small arterioles distal tubular structures.
within the kidney vessels (see images below).
Clinically, polyuria and concentrating defect are
During acute hypercalcemia, urinary concentrating defect can
Microemboli can also occur in the central nervous system and
lead to dehydration and may aggravate acute renal failure.
retinal arteries (called Hollenhorst plaques). In the extremities,
distal vessel emboli may result in small superficial skin infarcts (scabs).
Radiologic examinations may reveal nephrocalcinosis, and renal
stone formation can be a complicating factor in hypercalcemia.
More extensive cholesterol microembolization to the
extremities can result in the characteristic livedo reticularis
appearance in the lower extremities.
Oddly, some patients have other systemic signs and
symptoms, such as low-grade fever, leukocytosis,
eosinophilia, elevated sedimentation rate, and
Cholesterol microembolism usually causes acute renal failure of
varying degrees, with some spontaneous improvement in renal
function but often with permanent residual renal damage.
Kidney biopsy during the acute phase shows the characteristic
needle-shaped clefts caused by the cholesterol crystals
within the small- and medium-sized arterioles
accompanied by patchy tubulointerstitial nephritis with mild
mononuclear cellular infiltration.
No effective treatment for this disorder is available.
Balkan endemic nephropathy3,4 Physical
This is an endemic kidney disease confined to well-defined
A thorough physical examination may provide clues to the
discrete settlements located along the Danube River and its
diagnosis eg :
The caseload of patients is particularly heavy in the
o rash in acute tubulointerstitial nephritis,
Balkans (ie, Bosnia, Croatia, Yugoslavia, Romania,
o livido reticularis and
Bulgaria). The disease occurs in individuals,
o Hollenhorst plaques in the optic fundi in atheroembolic
autochthonous or immigrant, who have resided in
the endemic regions for at least 15-20 years and
does not occur among residents who move to
nonendemic areas. but, in most patients, no characteristic findings exist.
Thus, the evidence implicates environmental factor(s), but no Some patients present with hypertension, although others may
definitive agent or factor has been identified yet. be normotensive or hypotensive (eg, Balkan endemic
Typically, patients are nonhypertensive and have
disproportionately profound anemia. o Acute allergic tubulointerstitial nephritis:
Physical examination in acute tubulointerstitial nephritis
Patients are identified easily in the endemic regions by may show a rash accompanying renal findings.
However, rash is highly variable. Although the presence
checking for tubular proteinuria. Beta2 microglobulinuria of rash can be supportive evidence of an allergic etiology
has proved particularly useful in identifying cases and has been of an acute renal insufficiency, its absence is not
proposed and used as a marker of the disease.
useful in ruling out acute allergic interstitial
Because a major criterion to identify the disease is residency in
the endemic region, whether similar kidney diseases occur in o Cholesterol microembolic disease: In
other parts of the world is not known. cholesterol microembolic disease, eyeground
examination may reveal the characteristic cholesterol
Most patients eventually develop end-stage renal crystals, also termed Hollenhorst plaques, in retinal
disease and require dialysis. Up to 40% of patients develop vessels, which can support the diagnosis. Similarly, the
upper urinary tract uroepithelial tumors. presence of small skin infarcts or scabs, especially on or
between the toes or fingers, is a helpful clue to
cholesterol microembolism. Sometimes, particularly after
displacement of a large aortic plaque, marked ischemia of
Chinese herb/aristolochic acid the lower extremities yields a bluish-purplish discoloration
(ie, livedo reticularis) of the feet or lower portions of legs.
nephropathy o Atherosclerotic (ischemic) kidney disease:
Evidence for other atherosclerotic disease, such as
Chronic progressive tubulointerstitial nephritis has been carotid or inguinal bruits, may be clues to so-called
observed in many countries among patients using Chinese atherosclerotic kidney disease, particularly in elderly
herbal medicines for weight reduction. white males who smoke.
Most of these cases have been attributed to herbs
containing aristolochic acid.
The pathophysiology of nephrotoxicity is not well
understood. Renal biopsies have shown severe interstitial
nephropathy may not be an appropriate name
Causes for the disease, however, because aristolochic
acid can be present in herbal medicines from
Acute allergic interstitial nephritis: Any drug any country. The term aristolochic acid
can cause an acute allergic reaction involving the nephropathy (AAN) more accurately
kidneys. Drugs most commonly associated with acute characterizes this form of toxic nephropathy.
allergic nephritides are listed in History. o Another interesting feature of AAN is its
Cholesterol microembolic disease: association with uroepithelial cancers
Underlying atherosclerotic disease, dyslipidemia, and reminiscent of Balkan nephropathy. Aristolochic
smoking are conditions commonly associated with acid not only can trigger severe renal fibrosis
this disorder. Catheter manipulations above the level but also can cause oncogene mutations that can
of the renal arteries or anticoagulation in a patient explain the high incidence of renal cancer with
with atherosclerosis can trigger cholesterol this type of interstitial nephritis. Patients have
microembolic disease. also been found to have abnormal function of
Balkan endemic nephropathy: Epidemiology p53, a known tumor suppressor gene.
and natural history clearly implicate environmental
factors in the pathophysiology of this disease. Lead
contamination of food has been considered but ruled out
as a cause. Some studies have implicated a fungal toxin,
called ochratoxin, which can grow in moist grains in
storage and which has been shown to cause a similar
kidney disease in pigs in several central European
countries. However, most experts agree that the
evidence for its role in this endemic nephropathy is
weak. Acute Renal Failure
Lead nephropathy: Environmental and Glomerulonephritis, Acute
occupational exposure to lead can cause chronic Urinary Tract Obstruction
tubulointerstitial nephritis. Occupations in welding,
smelting, the battery industry, and mining have all been
responsible for lead nephropathy cases. Environmental
Other Problems to Be Considered
exposure from leaded gasoline is decreasing because
the use of leaded gasoline has ceased in the United Radiation nephritis
States. Sporadic exposure is still observed, particularly Toxic nephropathies
among children living in deteriorating housing in urban
areas. Rarely, lead poisoning can be observed among
individuals who consume moonshine whiskey and those
who drink beverages from imported ceramics painted
with leaded glaze.
Obstructive uropathy: A variety of causes
contribute to obstructive uropathy. Prostate disease
in elderly males and pelvic or colonic tumors involving
both ureters in both sexes can cause obstructive
uropathy. Nephrolithiasis, with or without urinary
tract infection, may also cause obstructive uropathy.
Radiation to the pelvic area and some drugs, such as
methysergide, can cause retroperitoneal fibrosis and
Chinese herb/aristolochic acid
o Aristolochic acid was recognized as a potent
nephrotoxin that can cause rapidly progressive
interstitial fibrosis and end-stage renal disease
in young women using a Chinese herb as part of
a slimming regimen in Belgium in early 1990s.
o Since then, many other cases of so-called
Chinese herb (CH) nephropathy have been
reported from around the world. CH
observed with lead nephropathy and NSAID-induced analgesic
nephropathy, among other conditions.
Urinalysis: Urinalysis may reveal :
o hematuria, and
o the presence of white cells,
o with or without bacteria
A microscopic analysis of urine sediment may reveal :
o white cells,
o eosinophils, and
If allergic interstitial nephritis is suspected, send a cytospin
specimen to determine if eosinophils are in the urine.
Laboratory Studies In NSAID-induced AIN, eosinophiluria is usually absent.
Complete blood cell count with differential:
Eosinophilia, when present, can be very helpful. However, this is
neither specific nor sensitive enough to establish the diagnosis.
Although the true incidence of eosinophilia in acute
tubulointerstitial nephritis is unknown, it is
estimated to be present in approximately half of
Unfortunately, the absence of eosinophiluria does not rule out the
diagnosis, and it can be observed in other diseases, including :
o cholesterol microembolism,
o urinary tract infections,
o parasitic disorders, and
Typically, eosinophilia is absent in AIN-induced by NSAIDs.
Blood chemistry: A complete set of chemistries, including
BUN and serum creatinine, provides information on whether renal
A low bicarbonate level (total carbon dioxide 24-23
mEq/L) may indicate acidosis.
Low serum potassium levels may indicate a proximal tubular
elevated serum potassium levels with a low bicarbonate
level may indicate type 4 renal tubular acidosis, which can be
Diagnosis of lead nephropathy requires
Ultrasonography: This noninvasive technique is extremely estimation of cumulative body stores of lead by either EDTA
helpful in identifying hydronephrosis in obstructive disease, as lead mobilization test or by determination of bone lead
well as calculi in stone disease. Both radiolucent and radiopaque content by radiographic fluorescence.
stones can be visualized using ultrasonography.
EDTA lead mobilization test is performed by measuring
A combination of ultrasonography and flat plate kidney, 24-hour urine lead excretion after intravenous or
ureter, and bladder (KUB) radiography is helpful in workup and intramuscular administration of 2 g EDTA (calcium
identification of radiopaque versus radiolucent stones. disodium versenate).
Normal kidney size by ultrasonographic examination generally favors Excretion of more than 0.6 g of lead per 24 hours is
but does not prove a diagnosis of acute (thus potentially reversible) considered an abnormal finding.
kidney disease. In contrast, small (shrunken) kidneys with
increased echogenicity indicate chronic and irreversible kidney
Blood lead levels, although elevated during
acute or recent exposure, are not very helpful
Computer-assisted tomography (CT) scanning: in the evaluation of chronic lead poisoning.
This technique provides information similar to ultrasonographic
scanning in the workup of kidney disease, generally with greater During acute exposure, lead is concentrated in the red blood
resolution. However, an ultrasonographic examination is sufficient cells and later extracted to tissues and bone as the red cells
in most kidney diseases. A high-resolution scan showing
microcalcifications in renal papillary tips can be very
helpful in diagnosis of analgesic nephropathy. The
kidneys may be very small in Balkan endemic nephropathy and Kidney biopsy is not diagnostic of lead etiology either and
aristolochic acid nephropathy. shows nonspecific changes such as interstitial fibrosis, tubular
atrophy, and vascular sclerosis, findings common to
tubulointerstitial nephritides of other etiologies. Body burden
of lead and bone lead concentration can be reduced by
extended chelation treatment using EDTA (versenate).
Intravenous pyelography: Once widely used, this
technique seldom plays a role in the workup of kidney diseases Quantitative determination of urine protein
in modern medicine. In many instances, similar information can
be obtained by ultrasonography without exposing the patient may be helpful.
to potentially nephrotoxic contrast dye.
Low-molecular weight proteins, such as beta-2
microglobulin, retinol binding protein (RBP), alpha-1
Gallium scanning: microglobulin, and immunoglobulin light chains, are
increased in chronic tubulointerstitial nephritides.
Findings on gallium scanning have been reported to be
confirmatory in the diagnosis of acute interstitial nephritis.
Thus, a negative finding helps to rule out this diagnosis. However,
Beta-2 microglobulinuria has been found helpful in the
findings on this test have proved to be too nonspecific, except as a diagnosis of Balkan endemic nephropathy and cadmium
confirmatory tool in suspected cases. nephropathy.
Kidney biopsy: Kidney biopsy is the definitive test for
Other Tests diagnosing acute allergic interstitial nephritis, particularly in cases
where clinical diagnosis is difficult. The differential diagnosis of acute
tubulointerstitial nephritis encompasses multiple etiologies, including
acute tubular necrosis, acute, vasculitis, and atheroembolic disease.
EDTA lead mobilization test Therefore, consider kidney biopsy when diagnosis is not obvious.
Kidney biopsy shows mononuclear and often eosinophilic cellular
infiltration of the renal parenchyma with sparing of the glomeruli (see
Consider the possibility of lead nephropathy in second and third images below). Sometimes, interstitial changes such
patients presenting with chronic renal insufficiency, as fibrosis and atrophy are also present.
hypertension, and gout. In the absence of documented
episodes of acute symptomatic lead poisoning, medical history
is not reliable in ascertaining the lead etiology in patients
presenting with chronic tubulointerstitial nephritis. Acute cellular infiltration, particularly with eosinophilia, can be
diagnostic of acute allergic interstitial nephritis (see first five
images below). In cholesterol microembolism in the kidney, the
finding of a characteristic needle-shaped cleft in medium- or Chelation therapy with EDTA may slow progressive
small-sized renal arterioles is diagnostic (see sixth and seventh
images below). Chronic tubulointerstitial nephritis is renal insufficiency in patients with mild lead
characterized by tubular atrophy, fibrosis, and patchy infiltrate intoxication. Several studies from Taiwan have shown that
of mononuclear cells chelation therapy in patients with modest increases in body lead
burden (ie, 80-600 µg of lead) significantly slowed and/or reversed the
rate of decline in the glomerular filtration rate (GFR) compared to
This was found in both diabetics and nondiabetics.6,7 Given
that these studies took place in Taiwan, it is difficult to generalize
Treatment – Medical Care these results. Further study is needed before this treatment can be
Treatment of acute tubulointerstitial
Because no effective therapy reverses the long-term
consequences of lead poisoning, the best therapy is
In most cases, cessation of the offending agent results in prevention and awareness of potential environmental and
quick recovery and complete resolution of the renal occupational sources for lead exposure.
disorder, although some patients progress to chronic renal
insufficiency. In patients with established lead nephropathy,
treatment consists of management of hypertension, gout,
and chronic renal insufficiency.
If no sign of improvement is observed within a few Many patients with lead nephropathy progress to end-
days of discontinuation of the offending agent, consider stage kidney failure and require dialysis.
therapy with steroids.
Although controlled trials are lacking, many authors suggest using
Treatment of cyclosporine/tacrolimus
prednisone at relatively high doses, eg, 1 mg/kg for induced renal failure:
4-6 weeks, with rapid tapering of the dose. This intervention may
improve the outcome, speeding renal recovery and reducing the
requirement for dialysis. Treatment includes reducing cyclosporine/tacrolimus doses
and target trough levels.
Discontinuing these medications and/or switching to other
Treatment of chronic tubulointerstitial immunosuppressives (eg, rapamycin), especially in those
with more advanced renal failure, should also be
Treatment depends on the etiology and generally consists of Diet
supportive measures, such as :
Hypertensive patients should be on a low-sodium diet.
o adequate blood pressure control and For all patients with early renal disease, recommend general
o management of anemia guidelines for a healthy diet, ie, low-fat (low-cholesterol) diet rich in
fresh fruits and vegetables such as the dietary approaches to stop
hypertension (DASH) diet.
Treatment of lead nephropathy
Chelation therapy is of proven value and must be
implemented in acute lead poisoning. Although the oral chelating
agent succimer (Chemet) has proved highly successful in treating
children, it has not been widely used in adults. Nevertheless, it
appears effective in reducing body lead stores.
Abrupt discontinuation of glucocorticoids may cause adrenal
hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease,
hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis,
growth suppression, and infections may occur with glucocorticoid use
For acute allergic interstitial nephritis, if no spontaneous
recovery in renal function is observed after cessation of the
offending agent, implementing a short course of steroid
therapy is generally recommended. No controlled studies exist on
the effect of corticosteroids. Therefore, no well-defined dosage and Chelating agents
duration exist. Most practitioners recommend a relatively high dose
(eg, 1 mg/kg prednisone) with a rapidly tapering regimen within several
weeks. These agents promote the excretion of lead.
Immunosuppressants for treatment of autoimmune disorders. Succimer (Chemet)
Metal chelator, analog of dimercaprol. Used in lead
Particularly useful in children with lead blood levels 45 mcg/dL.
Has anti-inflammatory properties and causes profound and varied
metabolic effects. Approved for chelation therapy in children for lead poisoning. Its
value in chronic lead nephropathy is not established.
Modifies the body's immune response to diverse stimuli.
o May decrease inflammation by reversing increased
capillary permeability and 10 mg/kg PO q8h for 5 d, followed by 10 mg/kg PO q12h for 14 d;
o suppressing PMN [= PML = polymorphonuclear leukocytes ] activity. repeat dosing may be necessary
o Stabilizes lysosomal membranes and
o suppresses lymphocytes and antibody production Precautions
Adult Renal or hepatic impairment; to prevent toxicity, patients should be
0.5-2 mg/kg/d PO, taper as condition improves; single am dose
safer for long-term use, but divided doses have greater anti-
o Coadministration with estrogens may decrease prednisone
o concurrent use with digoxin may cause digitalis toxicity
secondary to hypokalemia;
o phenobarbital, phenytoin, and rifampin may increase
metabolism of glucocorticoids (consider increasing
monitor for hypokalemia with
coadministration of diuretics
Edetate calcium disodium (Calcium
For lead chelation. Only the calcium disodium preparation
should be used. In the context of this article, use of this medication is
confined to testing, ie, to perform the EDTA lead mobilization test for Deterrence/Prevention
diagnosing lead etiology of chronic tubulointerstitial nephritis.
Extended therapy to reduce body lead stores may possibly be
beneficial. o Allergic interstitial nephritis: Early recognition
and prompt discontinuation of the offending drug are
o Lead nephropathy: Implement environmental
EDTA lead mobilization test: 2 g IV/IM; measures, such as removal of lead from indoor paint
and gasoline, and eliminate other sources of exposure.
for IV, dilute with 500 mL of D5W or 0.9% NaCl and infuse over 8-
Use caution with imported ceramics, particularly if
if IM used, mix with 5 mL of 2% lidocaine to avoid pain at injection
Administer as in adults; not to exceed 1 g/d
o Hypertension may complicate any renal disease,
but not all cases of interstitial renal disease are
associated with hypertension (ie, Balkan endemic
nephropathy, acute allergic interstitial nephritides).
o Electrolyte and acid-base disorders may be observed.
Follow-up o Chronic tubulointerstitial disease may progress to end-
stage renal disease, requiring dialysis or
Further Inpatient Care
Patients with acute renal failure or with serious
electrolyte or acid-base disorders may require
inpatient care until stabilization or resolution.
Further Outpatient Care Prognosis
Provide patients with acute interstitial nephritis with o Allergic interstitial nephritis: Most patients
follow-up care until resolution. recover renal function upon cessation of the offending agent.
Patients who do not recover renal function and those with chronic
o Cholesterol microembolic kidney disease:
Often, some spontaneous improvement in renal function
tubulointerstitial nephritis should receive long-term follow-up care to
occurs after the embolic event. Complete resolution of renal
ensure that :
insufficiency is rare, however.
o optimal control of blood pressure is achieved and o Chronic tubulointerstitial nephritides:
o to protect kidneys from further potentially nephrotoxic Although the natural history of these diseases varies depending
therapies and/or interventions on the etiology, most chronic tubulointerstitial renal disease
eventually progresses to end-stage renal disease. However, the
rate of progression is generally believed to be much
slower in tubulointerstitial nephritis compared to
eMedicine's Diabetes Center and Cholesterol Center.
Acute Kidney Failure,
Media file 1: Kidney biopsy. This is an example of acute
High Cholesterol, and Cholesterol FAQs. interstitial nephritis. The renal cortex shows a diffuse
interstitial, predominantly mononuclear, inflammatory
infiltrate with no changes to the glomerulus. Tubules in the
center of the field are separated by inflammation and
Mayo Clinic - Kidney Transplant. edema, as compared with the more normal architecture in
the right lower area (periodic acid-Schiff, 40 X).
nephritis: Make sure to Media file 2: Kidney biopsy. Shown here is an example of
acute interstitial nephritis. The diagnosis is based on the
obtain a thorough history active inflammatory infiltrate on the right with unaffected
of previously documented glomeruli. Interstitial edema and fibrosis are present on the
left side of the field, where some tubules show thickened
drug allergies before basement membrane (hematoxylin and eosin, 20 X).
prescribing a new drug.
Media file 3: Kidney biopsy. This image shows acute Media file 5: Kidney biopsy. This image shows acute
interstitial nephritis. The interstitium is expanded by interstitial nephritis. The mononuclear inflammatory
mononuclear inflammatory infiltrate and edema. Acute infiltrate contains abundant eosinophils, suggesting an
tubular damage is present; some tubules are distended and allergic etiology. Severe tubular damage is observed
contain granular casts (hematoxylin and eosin, 40 X). (hematoxylin and eosin, 40 X).
Media file 4: Kidney biopsy in interstitial nephritis. Acute Media file 6: Kidney biopsy. This image shows acute
crescentic glomerulonephritis. The glomerular tuft is interstitial nephritis. The inflammatory infiltrate forms an
compressed by the proliferation of epithelial cells, forming ill-defined granuloma, suggesting allergic or infectious
a crescent. The interstitium shows mononuclear etiologies. A partially destroyed tubule is present (periodic
inflammatory infiltrate and edema (periodic acid-Schiff, 40 acid-Schiff, 40 X).
Media file 7: Kidney biopsy. This image shows chronic
tubulointerstitial nephritis. The interstitium is expanded by
fibrosis, with distortion of tubules and periglomerular
fibrosis. Glomeruli do not show pathologic changes
(hematoxylin and eosin, 20 X).
Media file 8: Kidney biopsy in interstitial nephritis. This
image shows a cholesterol microembolism. The 2 arterioles
in the center are occluded by elongated crystals
(hematoxylin and eosin, 20 X).
Media file 9: Kidney biopsy in interstitial nephritis. This image
shows a cholesterol microembolism. The arteriole in the center of
the field has a thickened wall. The lumen is occluded by elongated
spaces, corresponding to dissolved crystals surrounded by cellular
reaction. The 2 glomeruli flanking the arteriole are sclerotic and
hardly recognizable (hematoxylin and eosin, 40 X).