1. Simple and Complex renal Cysts
By:
Nour-Eldin A Nour-Eldin

2. SIMPLE CYSTS
Simple cysts (in > 50% of population > 50 years) probably arise from obstructed tubules or ducts.
They do not, however, communicate with collecting system.
Most commonly asymptomatic; rare: hematuria (from cyst rupture), HTN,cyst infection. Mass effect from large cysts may cause dull ache or discomfort.

3. Radiographic features , IVP:
Lucent defect
"Beak sign" can be seen with large cysts.
Round indentations on
collecting system
Cortical bulge

4. Radiographic features , US:
Anechoic
Sharply marginated,
smooth walls
Enhanced through-transmission

5. Radiographic features , CT:
No significant enhancement
after IV contrast (<5HU)
Smooth cyst wall
Sharp demarcation
Cyst wall too thin to be seen by CT
Homogenous Water density (< HU)

6. Be Careful:
Cysts that contain calcium, septations, and irregular margins (complicated cysts)
need further workup
True renal cysts should always be differentiated from hydronephrosis, calyceal
diverticulum, and peripelvic cysts.
Differentiate renal cyst from hypoechoic renal artery aneurysm using color Doppler US and Angiography

7. Hydronephrosis:

8. Parapelvic Cyst
Calyceal Diverticulum

9. Renal Artery Aneurysm

10. Complicated CYSTS
Complicated cysts are cysts that do not meet the criteria of simple cysts and thus require further workup.

11. Bosniak Classification:
Category (Bosniak)
US Features
Workup
Type 1: Simple cyst
Round, anechoic, thin wall enhanced through transmission
None
Type 2: Mildly complicated cyst
Thin septation, calcium in wall
CT or US follow-up
Type 3: Indeterminate lesion
Multiple septae, internal echos mural nodules
Thick septae
Partial nephrectomy, biopsy
CT follow-up if surgery is
high risk
Type 4: Clearly malignant
Solid mass component
Nephrectomy

12. Radiographic Features of Complicated Cysts
Septations
Thin septa within cysts are usually benign.
Thick or irregular septa require workup.
Calcifications
Thin calcifications in cyst walls are usually benign.
Milk of calcium: collection of small calcific granules in cyst fluid: usually benign
Increased CT density (> 15 HU) of cyst content
Vast majority of these lesions are benign.
High density is usually due to hemorrhage, high protein content, and/or calcium.
Thick wall
These lesions usually require surgical exploration.

13. Simple renal cyst, Bosniak Category I.

14. Bosniak Category II cyst
Curvilinear calcification within a thin septum

15. Bosniak Category II cyst
Homogeneously hyperdense mass
No increase in Density after IV contrast

16. Bosniak Category II cyst
Cyst with several internal septations and a minimally thickened wall

17. Bosniak Category II cyst.
Cyst with uniform, mild wall thickening and short, interrupted calcifications

18. Bosniak Category II hyperdense cyst.

19. Bosniak Category II cyst

20. Bosniak Category II cyst.
Nearly completely calcified mass with no obvious
enhancing elements

21. Bosniak Category II.
subcentimeter rim calcified renal cyst

22. Bosniak Category III. cystic mass with irregular wall thickening and
associated heterogeneous nonenhancing elements

23. Bosniak Category III complex cyst.
multilocular, encapsulated mass

24. Bosniak Category III complex cyst.
Thick-walled, encapsulated, multilocular cystic mass with enhancing septa

25. Bosniak Category IV cystic neoplasm.

26. Bosniak Category IV cystic neoplasm

27. A 42-year-old female with back pain, hematuria, and a renal mass discovered by lumbar spine MR.
hyperdense (55 HU) 3 cm mass.
enhance to 88 HU after IV contrast
Renal cell carcinoma

28. Thank you
Thank you