Transcript Atypical Renal Cysts - Urology Department PCH

Mr Will Finch MBBS BSc(Hons) MRCS
Urology SpR
Edith Cavell Hospital
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When to….
Discharge, survey or operate
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Category I.
 simple benign cysts showing homogeneity, water content, and a sharp interface with adjacent renal
parenchyma, with no wall thickening, calcification, or enhancement.
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Category II.
 cystic lesions with one or two thin (≤ 1 mm thick) septations or thin, fine calcification in their walls or
septa (wall thickening > 1 mm advances the lesion into surgical category III) and hyperdense benign
cysts with all the features of category I cysts except for homogeneously high attenuation. A benign
category II lesion must be 3 cm or less in diameter, have one quarter of its wall extending outside the
kidney so the wall can be assessed, and be nonenhancing after contrast material is administered.
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Category IIF
 minimally complicated cysts that need follow-up. This is a group not well defined by Bosniak but
consists of lesions that do not neatly fall into category II. These lesions have some suspicious
features that deserve follow-up up to detect any change in character.
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Category III.
 true indeterminate cystic masses that need surgical evaluation, although many prove to be benign.
They may show uniform wall thickening, nodularity, thick or irregular peripheral calcification, or a
multilocular nature with multiple enhancing septa. Hyperdense lesions that do not fulfill category II
criteria are including in this group.
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Category IV.
 nonuniform or enhancing thick wall, enhancing or large nodules in the wall, or clearly solid
components in the cystic lesion. Enhancement was considered present when lesion components
increased by at least 10 H.
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Number of septae
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Group 1
Group 2
Group 3
Group 4
No septae
1-4 septae
5-9 septae
>9 septae
Thickness of wall and/or septae
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Group 1
Group 2
Group 2F
Group 3
Wall only
Hairline thin
Minimally thickened
Grossly thickened (>1mm) and
irregular
Israel et al. Radiology 2004;231:365-71
Bosniak Cat. n. malignancies/ n. in group
Ref
I
II
III
IV
[5]
0/22
1/8
5/11
26/29
[15]
-
0/4
4/7
5/5
[16]
½
1/7
4/13
7/10
[17]
0/7
4/5
4/4
6/6
29/49
18/18
[18]
0/15
[19]
-
3/28
8/29
-
[20]
-
-
28/179*
-
[21]
-
-
17/28
-
[23]
0/11
1 /2
10/10
12/12
Total
1/57
10/54
109/330
74/80
1.7
18.5
33.0
92.5
% CANCER
Warren et al. BJUI 2005;95:939-42
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37 patients
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Stage II
Stage IIF
Stage III
Stage IV
6 pts
No cancers
10 pts 2 cancers (20%)
14 pts 4 cancer
(30%)
7 pts
6 cancer
(86%)
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Stage I&II
Stage IIF
Stage III&IV
No Follow up required
Indeterminate risk requires FU
Surgical management
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41 patients with Stage IIF
Nearly 6yrs FU
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36 masses remained unchanged on CT
3 masses got smaller
These were considered benign
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2 lesions increased in size and were removed, both
were RCC’s
Israel G, Bosniak Ml. Am J Roentgenol 2003;181:627-3
Does Stage IIF improve accuracy of Bosniak classification?
O’Malley et al. J Urol 2009;182(3):1095
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112 pts
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Stage IIF
Stage III
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Median FU of 15 months
81 pts
31 pts
14.8% of Bosniak IIF lesions progressed in complexity (median of 11 months)
No differences in tumour or patient characteristics for cysts that progressed and those
that remained stable
 33 patients with Stage III cysts had surgery
 Malignancy rate 81.8%
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Suggests increased accuracy of classification by low rate of progression (14.8%) for
Bosniak IIF, and very high rate of malignancy in Stage III group (81.8%)
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Stage I
No FU
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Stage II
No FU
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Stage IIF
Scan @ 6/12 and 1yr
If no evidence of
progression – discharge?
Or
Scan @ 6/12, 1yr and 2yrs
and then discharge?
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Stage III/IV
Surgical exploration
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No good quality studies to answer question of FU
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Subjective assessment on USS, less so on CT
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It appears that if Stage IIF diagnosed accurately
 Low risk of progression ~ 15% - 20%
 Progression occurs on average around 1yr
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Would be sensible that accurate rpt imaging reflects this
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Classification based on CT, but role for MRI or CEUS
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Individual patients choice re balance of risk and FU or
exploration?