The Decoy Cell

1
The Decoy Cell
Lukas Bubendorf, Michael J. Mihatsch Institute
for Pathology, University Hospital Basel
2
Decoy Cells

• Decoy cells in urinary tract (early 1960s)
• May be mistaken for carcinoma cells
• Cave BK-Virus nephropathy (BKN) in 5 kidney
  transplant recipients

3
Decoy Cells
Systematically analysed in all urine samples
since 1980 (gt 10 000 samples)
4
Occurrence of Decoy cells
Pregnancy 3 Diabetes mellitus 3 Cancer
patients 13 Healthy renal Tx
recipients 23 Healthy pulm Tx recipients 11 Hear
t-TX BM-TX rare
5
Variants of BK Virus Infected Tubular Cells in
Histology
A) tumor-like
B) vesicular
C) CMV-like
D) amorphous
6
Decoy Morphology
EM
ground-glass (classic Type)
7
Vesicular Type
8
spider web-like, reticular chromatin (peculiar
network of chromatin L.Koss)
9
spider web-like, reticular chromatin
10
Hyperchromatic und polymorphic (carcinoma-like)
11
granular inclusion-body
12
SV40
(SV40, Calbiochem ABC-Elite Methode, 1500
AG-retrieval DK 5 min AEC)
13
SV40
SV40
14
(n 6 Patienten)
15
Where do the Decoy Cells come from? Donor or
Recipient?
16
Decoy XX (donor)
Sex-chromosome status in Decoy cells
(sex-mismatch)
Urothel XY (recipient)
17
A
n3
Nephrectomy
B
n2
Switch
to
low
dose
CSA
18
Special Findings in Urine Samples
19
Stage C often many neutrophils
20
Dirty background
21
Dirty background
22
Significance of Urine Sample Composition (n25)
BKN pos n () Decoy Cells only n ()   p a
Detritus 9 (75) 11 (84) 0.5476
Epithelial cells 6 (50) 10 (77) 0.1583
Neutrophils 12 (100) 12 (92) 0.2459
Mononuclear cells 3 (25) 1 (8) 0.2307
Bacteria 7 (58) 8 (62) 0.8702
Red blood cells 10 (83) 10 (77) 0.6879
achi square test
23
Get ready for the Quiz!
Train yourself in the recognitionof decoy cells
on virtual slides http//vmic.unibas.ch/patho/semi
nar/ K. and D. Glatz
24
1
Reactive urothelial cells
25
2
Carcinoma in situ of the urinary bladder
26
33
3
Decoy cells (classic vesicular type)
27
4
Low-grade non-invasive bladder cancer (pTa)
28
5
Decoy cells (classic)
29
5
Decoy cells in non-invasive bladder cancer (pTa)
30
6
Pseudo-Decoys
High-grade bladder cancer (Pseudo Decoys)
31
7
Decoy cells (hyperchromatic type)
32
8
Decoy cells (reticular type)
33
9
Decoy cells (classic type)
34
Screening Algorithm
35
Cumulative Prevalence of BKN
Cumulative Prevalence
Green gt300 lit. Red Basel n39
TX to BKN (Week)
36
Time Dependent Cumulative Prevalence of DC,
Viremia and BKN
Cumulative Prevalence
Days after Tx
37
Risk for BKN Studied in 2020 Urine Samples
Risk for BKN Smear DC/10HPF Cytospin DC/10HPF
Low risk Sensitivity gt90 lt3 lt3
Control range 3-60 3-200
High risk Specificity gt90 gt60 gt200
38
Risk for Viremia studied in 600 Blood Samples
with PCR
Risk for Viremia Smear DC/10HPF Cytospin DC/10HPF
Low risk Sensitivity gt90 lt2 lt2
Contol range 2-60 2-100
High risk Specificity gt90 gt60 gt100
39
Immunohistochemistry for Cells of the Proximal
Tubule and Collecting Duct

BKN pos (n/) N12 BKN neg (n/) N13 P a
Prox. Tub. (AMACR) 7 (58) 2 (15) 0.0094
Collect. D. (U.europ) 5 (42) 3 (23) 0.2260
achi square test
40
Ulex europaeus SV40 (IF)
SV40
AMACR (ICC) (Alpha-Methylacyl-CoA Racemase)
41
Decoy Cells and Risk Factor for BKN
42
Material
Patients (n) Biopsies (n) Urines (n)
No DC 685 2011 gt1500
lt5 DC 181 527 gt1000
gt5 DC 129 471 gt2000
gt5 DC No BKN 90 284 gt1276
gt5 DC Plus BKN 39 187 846
43
Risk factors for BKN

• Factors evaluated
• Sex
• Age of recioient
• Age of Donor
• Basic disease
• Source of kidney cadaver donor
• living donor (related, unrelated)
• No of transplants
• Sex mismatch
• HLA Mismatch
• Panel reactive antibodies
• Iscaemia warm, cold
• Findings in diagnostic biopsies
• Findings in zero hour biopsies
• Imunnosuppression

44
Male?
Odds ratio 2.3
gt50 years of age
Negative BKV serostatus
No
Not studied
Patients at risk
Impaired BKV spec T cell response
White ethnicity
Not studied
Not studied
Sex mismatch female to male possible
45
HLA mismatch?
Pre-existing Tx-damage
No
No
Organ factors
Calcineurin-inhibitor toxicity?
Prior acute rejection
No
Odds ratio 2.5
46
High dose
Tacrolimus
yes
Odds ratio 4.0
Immunosupression
Anti-rejection treatment in presence of allograft
injury
Mycophenylate Mofetil
Odds ratio 3.0
ATGAM Odds ratio 4.5
47
No Decoy cells No BKN