Clinical History
A 50-year-old, non-diabetic, non-hypertensive male patient presented with right sided flank pain and pyuria for the past 6 months. He had a history of pulmonary tuberculosis 20 years before. Anti-tubercular drug therapy defaulter. Creatinine level was 618.8 µmol/L.
Imaging Findings
Non-enhanced axial, reformatted coronal and sagittal CT examinations of abdomen and pelvis demonstrate rim-like calcifications with dense punctate calcifications within, in the entire parenchyma of right kidney. Low attenuation areas suggest complete necrosis of the kidney. Also coronal image shows shrunken kidney as compared to normal left kidney.
Discussion
Definition:
"Putty kidney" is an end-stage renal tuberculous disease with sacs of caseous, necrotic material and autonephrectomy (small, shrunken kidney) with dystrophic calcification. [1]
Background:
- Genitourinary tract is the second most common site of tuberculous infection after lungs
- Men are more commonly infected than women, most often < 50 years old
- Spread is haematogeneous and usually occurs with primary exposure
- Although may not be clinically apparent at this time, remaining latent for decades
- Only about 25% of patients with genitourinary tuberculosis have a known history of pulmonary TB
Pathophysiology:
- Begins as small tubercle and extends to renal tubules and medulla as necrotizing lesions produce larger cavities which communicate with collecting system
- Stricturing eventually results in a fibrotic and small kidney
- Prostatic TB is from descending infection, unlike involvement of seminal vesicles
Clinical Features: Haematuria (microscopic or macroscopic), stone formation, dysuria and urgency of micturition, pyuria [2]
Imaging Findings:
Plain films: May show large globular, amorphous calcifications or smaller nondescript stones
Intravenous pyelography (CT urograms can be diagnostic):
- Affected kidney may contrast-enhance on CT
- Renal calcification is common (24-44%)
- Stones, focal or extensive globular calcification, ring-like calcifications of papillary necrosis
- Cortical scarring
- "Smudged" papillae (moth-eaten) – irregular due to inflammation and necrosis
- Several cysts surrounding a calyx with cortical thinning
- Infundibular strictures
- Hydrocalyces without dilatation of renal pelvis, or
- Hydronephrosis
- About 75% unilateral radiologically
Ureters:
- Usually the upper or lower third (more common)
- Beading (sawtooth ureter), corkscrew, strictures
- Bladder involvement rarely leads to calcification of wall
- Reflux, thickening of bladder wall (thimble bladder), fistula formation
Ultrasound: Hypoechoic masses with hydronephrosis, calcifications [2, 3]
Treatment:
Anti-tuberculous drugs
Nephrectomy
Complications:
If untreated, end result is autonephrectomy
Infertility in women
Sinus and fistula tract formation
Prognosis:
With anti-tuberculous drugs, mortality is low (2%) [3]
Differential Diagnosis List
Putty right kidney with changes of early auto-nephrectomy in an anti-tubercular drug therapy defaulter
Xanthogranulomatous pyelonephritis
Hydatid cyst
Final Diagnosis
Putty right kidney with changes of early auto-nephrectomy in an anti-tubercular drug therapy defaulter
