Histopathology and TB-PCR kit analysis in differentiating the diagnosis of intestinal tuberculosis and Crohn’s disease

Table 1 Disease location of ITB and CD n (%)

Involving site	ITB	CD
Right colon	32 (58.2)	14 (33.3)
Left colon and rectum	4 (7.3)	4 (9.5)
Skip lesion or pancolitis	19 (34.6)	24 (57.1)

ITB: Intestinal tuberculosis; CD: Crohn’s disease.

Table 2 Comparison of histopathologic parameters between ITB and CD n (%)

Histologic parameters	Cases		P value
	ITB (n = 52)	CD (n = 26)
Size of granuloma			0.000
Small (< 200 μm)	6 (11.5)	13 (50.0)
Medium (200-400 μm)	7 (13.5)	7 (26.9)
Large (> 400 μm)	39 (75.0)	5 (19.2)
Granuloma/piece > 11	24 (46.2)	9 (34.6)	0.331
Giant cells	25 (45.5)	5 (19.2)	0.015
Caseation necrosis	14 (26.9)	0 (0.0)	0.003
Confluent granuloma	24 (46.2)	2 (7.8)	0.001
Discrete granuloma	30 (57.7)	3 (11.5)	0.000
Lymphoid cuff	31 (59.6)	9 (34.6)	0.037
Ulcer with histiocytes2	17 (30.9)	3 (11.5)	0.056

¹More than one granuloma per biopsy piece;

²Ulcer with band of epithelioid histiocytes.

Table 3 Classification of ITB and CD according to histopathologic parameters n (%)

Group	ITB (n = 55)	CD (n = 42)	Re-classification of ITB (n = 55)
I	14 (25.5)	0 (0.0)	ITB group: 26 (47.3)
II	12 (21.8)	1 (2.3)
III	23 (41.8)	15 (35.7)	Confusing group: 29 (52.7)
IV	6 (10.9)	26 (61.9)

Group I showing caseation necrosis; Group II showing more than four kinds of histopathologic parameters without caseation necrosis; Group III showing one to four kinds of histopathologic parameters without caseation necrosis; Group IV without any histopathologic parameters.

Table 4 Results of TB-PCR in gold standard

	Positive control (n = 9)	Negative control (n = 10)	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
Kit <A>	8	10	88.9	100	100	90.9
Kit <B>	8	10	88.9	100	100	90.9
In-house	6	10	66.7	100	100	71.4

TB-PCR: Polymerase chain reaction for Mycobacterium tuberculosis; PPV: Positive predictive value; NPV: Negative predictive value.

Table 5 Results of TB-PCR in ITB and CD

TB-PCR test	ITB (n = 55)		CD (n = 42)		Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	P value
	+	-	+	-
Kit <A>	25	30	5	37	45.5	88.1	83.3	55.2	0.000
Kit <B>	20	35	0	42	36.4	100	100	54.5	0.000
In-house	3	52	0	42	5.5	100	100	44.7	0.256

Table 6 Histopathologic parameters and TB-PCR n (%)

Confirmed diagnosis	Group of HPP	n	TB-PCR positive cases
			Kit <A>	Kit <B>	In-house
ITB	I	14 (25.5)	9 (64.3)	10 (71.4)	2 (14.3)
	II	12 (21.8)	6 (50.0)	4 (33.3)	0 (0.0)
	III	23 (41.8)	9 (34.6)	6 (23.1)	1 (3.8)
	IV	6 (10.9)	1 (33.3)	0 (0.0)	0 (0.0)
CD	I	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)
	II	1 (2.3)	0 (0.0)	0 (0.0)	0 (0.0)
	III	15 (35.7)	4 (15.4)	0 (0.0)	0 (0.0)
	IV	26 (61.9)	1 (6.3)	0 (0.0)	0 (0.0)

HPP: Histopathologic parameters.

Table 7 Comparison of diagnostic accuracy of ITB before and after combination of histopathology and TB-PCR

	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	P value
Histopathology	47.3	100	100	59.2
Combination with kit <A>	65.5	88.1	87.8	66.1	0.390
Combination with kit <B>	58.2	100	100	64.6	0.010
Combination with in-house PCR	49.1	100	100	60.0	0.320