- A putty kidney refers to a pattern of renal calcification seen on radiography in renal tuberculosis. It is characterized by homogeneous, ground-glass calcification over 1 cm in diameter, representing calcified caseous tissue.
- Renal tuberculosis can involve the renal parenchyma and collecting system, resulting in pyelonephritis-like appearances, pseudotumoral nodules, or end-stage changes with progressive hydronephrosis and dystrophic calcification.
- Imaging findings on plain radiography, IVU, ultrasound and CT vary according to the stage of disease, but typically include renal calcifications, papillary necrosis, multifocal strictures, hydronephrosis, and thin parenchy
2. INTRODUCTION
• A putty kidney refers to a pattern of renal calcification associated with renal
tuberculosis conventionally described on plain radiography.
• Calcification is usually homogeneous and ground glass-like, representing
calcified caseous tissue
• Premkumar et al. Labelled calcification 'putty-like' if any faint area of uniform
calcification was more than 1 cm in diameter
• Lobar calcification represents an end-stage appearance, associated with
autonephrectomy.
3. GENITOURINARY TUBERCULOSIS
• The genitourinary tract is a primary target of hematogenous infections and is
the most common site of extra-pulmonary TB
• Genitourinary tuberculosis (GUTB), a term coined by Wildbolz in 1937
• A worldwide disease, but shows a more destructive behavior in developing
countries
• The kidney is the most common site of GUTB
• Increased incidence of extra-pulmonary TB has been noted in AIDS
4. PATIENT POPULATION
• GUTB usually affects adults between the second and fourth decades of life
• There is often a long latent period (5-40 years) between the original pulmonary
infection and the appearance of clinical renal disease, which is probably why
renal involvement is rare before the age of 20 years
5. SYMPTOMS
• Frequent voiding; dysuria; pyuria
• Back, flank or abdominal pain
• Microscopic or macroscopic hematuria
• Hematuria and culture-negative pyuria may be seen at urine analysis
• Urine analysis of sediment from a 24-hour specimen for acid-fast bacilli (AFB) is
positive in 80-90% of cases of TB
6. RENAL TUBERCULOSIS
• Renal tuberculosis, a subset of genitourinary tuberculosis, accounts for 15-20%
of extra-pulmonary tuberculosis
• Tuberculosis can involve both the renal parenchyma and the collecting system
(calyces, renal pelvis, ureter, bladder and urethra) and results in different
clinical presentations and radiographic appearances
7. PATHOLOGY
• Renal infection results from hematogenous spread at the time of primary
infection, with multiple micro-abscesses developing at the site of peri-
glomerular capillary seeding
• Usually there is a long latency between primary infection and presentation which
in most case occurs due to host immunity becoming compromised
• These quiescent granulomas then can reactivate, grow and eventually
communicate with the calyces, leading to downstream infection
8. RADIOGRAPHIC FEATURES
• Both the renal parenchyma and the upper collecting system (calyces and renal
pelvis) can be involved
• Infection limited to the renal parenchyma has two morphological appearances
• Pyelonephritis
• Appearances are similar to pyelonephritis caused by other organisms
• Hypoperfusion and swelling of all or part of the kidney
• Pseudotumoural type
• Single or multiple nodules
• Mimics renal cell carcinoma
9. • Usually the collecting system is involved (either in isolation or in combination
with the parenchyma), and appearances vary according to the stage of disease
• Early
• Papillary necrosis (single or multiple) resulting in uneven caliectasis
• Progressive
• Multifocal strictures and hydronephrosis
• Mural thickening and enhancement (on cross-sectional imaging)
• End-stage
• Progressive hydronephrosis and parenchymal thinning
• Dystrophic calcification
10. PLAIN RADIOGRAPH
• Plain film findings focus on calcification, which is seen in ~35%
(range 25-45%), at various stages of disease:
• Triangular in papillary necrosis
• Focal or amorphous: putty kidney (end stage)
11. IVU
• Traditional plain film IVU is quite sensitive to renal tuberculosis.
• Features include:
• Parenchymal scars 50%
• Moth eaten calyces: early finding
• Irregular caliectasis
• Phantom calyx
• Hydronephrosis
13. ULTRASOUND
• Sonographic appearances are nonspecific and variable, depending on the stage
of disease.
• Early
• Normal kidney or small focal cortical lesions with poorly defined border
• Calcification +/-
•End-stage
•Small, shrunken kidney, "paper-thin" cortex and dense dystrophic
calcification in collecting system
•May resemble chronic renal disease
14. •Progressive
o papillary destruction with echogenic masses near calyces
o distorted renal parenchyma
o irregular hypoechoic masses connecting to collecting system; no renal pelvic dilatatio
o mucosal thickening +/- ureteric and bladder involvement
o small, fibrotic thick-walled bladder
o echogenic foci or calcification (granulomas) in bladder wall near ureteric orifice
o localized or generalized pyonephrosis
15. • Ultrasound is less sensitive than CT in detection of:
• Calyceal, pelvic or ureteral abnormalities
• Isoechoic parenchymal masses
• Small calcifications
• Small cavities that communicate with collecting system
16. CT
• CT is the most sensitive modality for visualizing renal calcifications and CT IVP
is more sensitive at identifying all manifestations of renal tuberculosis
• Early
• Papillary necrosis (single or multiple) resulting in uneven caliectasis
• End-stage
• Progressive hydronephrosis results in very thin parenchyma, mimicking multiple
thin walled cysts
• Amorphous dystrophic calcification eventually involves the entire kidney (known
as putty kidney)
17. • Progressive
• Multifocal strictures can affect any part of the collecting system
• Generalised or focal hydronephrosis
• Mural thickening and enhancement
• Poorly enhancing renal parenchyma, due to direct involvement or due to
hydronephrosis
20. TREATMENT AND PROGNOSIS
• Multi-drug treatment is essential, however despite treatment, structuring can
progress
• The role of nephrectomy is controversial
• Nephrectomy, partial nephrectomy can be performed both open and
endoscopically
21. DIFFERENTIAL DIAGNOSIS
XANTHOGRANULOMATOUS
PYELONEPHRITIS
• Rare form of chronic
pyelonephritis and
represents a chronic
granulomatous disease
resulting in a non-
functioning kidney
• Female predilection (F:M
2:1) presumably relating
to an increased incidence
of urinary tract infections
and thus struvite
NEPHROCALCINOSIS
• previous known as
Anderson-Carr kidney or
Albright's calcinosis, refers
to the deposition of calcium
salts in the parenchyma of
the kidney
• Types:
• medullary
nephrocalcinosis: 95%
• cortical nephrocalcinosis:
5%
• combined cortical and
medullary nephrocalcinosis
MEDULLARY SPONGE
KIDNEY
• Medullary sponge kidney
is a sporadic condition
where the medullary and
papillary portions of the
collecting ducts are
dysplastic, and dilated
and in most cases
develop medullary
nephrocalcinosis.
22. XANTHOGRANULOMATOU
S PYELONEPHRITIS
• A chronic granulomatous
process
• The kidney is eventually
replaced by a mass of
reactive tissue, surrounding
the usually present (90%)
inciting staghorn calculus
with associated
hydronephrosis of a greater
or lesser degree. Foamy
(lipid-laden) macrophages
predominate
• Fragmentation and
enlargement of the the renal
outline may be seen. A
calculus is seen
MEDULLARY
NEPHROCALCINOSIS
• Deposition of calcium salts in
the medulla of the kidney.
• Due to the concentrating
effects of the loops of Henle,
and the biochemical milieu of
the medulla, compared to the
cortex, it is 20 times more
common than cortical
nephrocalcinosis
• Causes: hyperparathyroidism,
medullary sponge kidney,
renal tubular acidosis,
hypervitaminosis D, milk-
alkali syndrome, sarcoidosis.
• Hypercalciuric states
• Cushing syndrome
• multiple myeloma
• Bartter syndrome
MEDULLARY SPONGE
KIDNEY
• It represents a
developmental defect
affecting the formation of
collecting tubules and
results in cystic dilatation of
medullary and papillary
portions of collecting ducts.
• Clusters of pyramidal
medullary calcification are
characteristic. Delayed post
contrast CT may
demonstrate a "paint brush"
appearance to the renal
medullary regions
23. XGPN
• Ultrasound examination
demonstrates an enlarged
and distorted renal outline,
with loss of the normal
renal architecture and
(usually) a centrally-located
shadowing calculus
• CT findings are most
helpful in reaching the
correct diagnosis. The
normal renal outline is lost
and enlarged with a
paradoxical contracted
renal pelvis. The calyces in
CORTICAL NC
Causes:
• renal cortical necrosis
• chronic glomerulonephritis
• Alport syndrome
• chronic pyelonephritis
• hyperoxaluria
• oxalosis
• vesicoureteral reflux (VUR)
• nephrotoxic drugs, e.g.
Amphotericin B
• autosomal recessive
polycystic kidney disease
(ARPKD)
MSK
• On IVP, pyelogram may
give a characteristic
bouquet of flowers
appearance
• Ultrasound of the
kidneys of patients with
medullary sponge
kidneys typically
demonstrates echogenic
medullary pyramids.
A phantom calyx is a solitary calyx which fails to opacify with contrast amidst an otherwise well-opacified pelvicalyceal system. It is due to an intrarenal process which has infiltrated and caused obliteration of the involved collecting system element.
It may be seen in:
tumour: especially transitional cell carcinoma of the renal pelvis
renal tuberculosis
acute pyelonephritis
renal calculus
renal ischaemia
renal trauma
congenital anomaly
renal contusion
technical underfilling
If the calyx is dilated and filled with tumour (but still visible) then it is referred to as an oncocalyx
Kerr kink a sign of renal tuberculosis. Scarring leads to a sharp kink at the pelvi-ureteric junction.