Vol 43 # 3 September 2011 - Kma.org.kw

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Correlation of Fine Needle Aspiration Cytological Features of Extra-pulmonary ...
September 2011
Table 3: Correlation of cytomorphological spectrum with AFB positivity in smears and culture
Cytological
spectrum
Total cases
n (%)
Cases with
ZN stain
n
AFB positive
(ZN Stain)
n (%)
Cases with mycobacterial
culture done
n
Mycobacterial
culture positive
n (%)
Granulomas with necrosis
Granulomas alone
Necrosis alone
Acute inflammatory exudate
Total
202 (53.0)
59 (15.5)
53 (13.9)
67 (17.6)
381
161
38
43
50
292
75 (46.6)
3 (7.9)
25 (58.1)
11 (22)
114 (39)
98
30
25
26
179
52 (53.1)
2 (6.7)
14 (56)
4 (15.4)
72 (40.2)
ZN-Ziehl Neelsen, AFB- acid fast bacilli
culture in 179 cases. The frequency of mycobacterial
positivity by the two methods correlated with the
cytomorphological features is highlighted in Table 3.
AFB were readily identified by ZN stain and culture in
25 of 43 (58.1%) of Group C (necrosis alone) and 11 of 50
(22%) of Group D (acute inflammatory exudates) cases.
In 109 cases, both ZN stain and mycobacterial culture
were available. In 32 of those cases both methods were
positive for AFB. In the 77 cases negative for AFB by
ZN stain, the mycobacterial culture was positive in 24
(31.2%) and negative in 53 (68.8%).
DISCUSSION
TB remains a major public health problem
worldwide. A definitive and accurate diagnosis of TB is
important because satisfactory results can be achieved
with chemotherapy alone, obviating surgery [9] . FNA
has provided an alternative and easy procedure
for collection of material for cytomorphological
and bacteriologic examination [2,5,8] . In smears with
necrotizing granulomas, the diagnosis of TB can be
suggested irrespective of AFB positivity. However, any
acellular necrotic or inflammatory material must be
subjected to AFB staining and culture so as not to miss
the diagnosis of TB [2] . Few reports are available from
the Middle East to document these findings [3,6,7,9-11] . We
have tried to correlate the cytomorphological findings
and AFB positivity in FNAC samples of palpable
masses.
The highest rate of AFB positivity was found in
necrotic material (58.1%) and a previous study from
Kuwait also reported maximum positivity (63%) in
TB lymphadenitis [6] . In granulomatous lesions we
detected AFB in 7.9% of cases by ZN stain and 6.7% by
culture. However, Gupta et al [6] found 20% and 40% of
granulomatous lymphadenitis to be positive for AFB
by ZN stain and culture respectively in their study.
In aspirates with acute inflammatory exudate, AFB
was found in 11 of 59 cases by ZN stain and 15.4%
by culture. In the absence of ZN staining, these cases
would have been reported as suppurative lesions. In
the negative smears on ZN staining, mycobacterial
culture was positive in 24 of 77 cases (31.2%). Eighteen
percent of 157 aspirates from suspected lymph nodes
were positive by ZN smear and 45% by culture [12] and
in this study [12] , culture identified AFB in 12 aspirates
with an inflammatory exudate alone. Culture positivity
has been reported to be significantly higher than smear
positivity [6,13] .
Table 4 correlates the AFB positivity by ZN stain
and the cytomorphological spectrum in fine needle
aspirates reported in various series [5,6,9,16-18] . The AFB
positivity in FNA with granulomas with necrosis
ranged from 14.3 [18] to 75.6% [9] , while in our study, it
was 46.9%. However, the detection of bacilli when
granulomas alone were identified, ranged from 1.9 [17]
to 28.5% [9] . In our study, we could demonstrate AFB
in 7.9% of the FNA with granulomas alone. The AFB
positivity was high 58.1% in our study, when necrosis
alone was seen in aspirates and literature review shows
it to range from 17.8 [17] to 68.7% [9] . In many studies,
details on AFB staining of FNAC showing an acute
inflammatory exudate alone are not available. Two
studies report AFB positivity in 35.8 [18] and 42.9% [16] of
Table 4: AFB positivity and cytomorphologic spectrum in FNA smears from tuberculous lesions
Authors reference (% positivity of ZN Stain)
Cytological
spectrum
Kumar
et al [18]
Das
et al [5]
Kakkar Prasoon [17] Gupta
et al [16] et al [6]
Ergete &
Bekel [9]
Present
study
Granulomas with necrosis
Granulomas alone
Necrosis alone
Acute inflammatory exudate alone
All cases
14.3
-
26.2
35.8
33.5
31.9
-
36.6
-
-
21.4
-
88.8
42.9
38.6
19.1
1.9
17.8
-
-
32
20
32.2
-
75.6
28.5
68.7
71.7
46.6
7.9
58.1
22
39
AFB - Acid Fast Bacilli, ZN - Ziehl-Neelsen