CASE 48 (February 2010)
A female preterm newborn (gestational age: 32 weeks), without a known cause of the premature birth, presented several episodes of gross hematuria during the first weeks of life. Ultrasound showed a right central intrarenal mass with involvement of a large portion of the kidney, 2.6 cm in diameter. The presumptive diagnosis was hematoma versus neoplasm.
No a procedure was performed and the infant remains under observation with ultrasound monitoring. The mass was growing at the same rate that the kidneys, and there was not extrarenal extension. There was not other lesions in kidneys or other organs. She had a good general condition, asymptomatic, growing within the expected range, feeding well. No fever. Laboratory tests without alterations.
At 4 months of age a nephrectomy was carried out.
Look at the images.
Figure 1. Macroscopic image of the kidney sectioned longitudinally.
Figure 2. H&E, X100.
Figure 3. H&E, X200.
Figure 4. H&E, X100.
Figure 5. H&E, X200.
Figure 6. H&E, X400.
Figure 7. H&E, X400.
Figure 8. Methenemine-silver stain, X200.
Figure 9. H&E, X200.
What is your diagnosis?