Synovial histopathology of psoriatic arthritis, both oligo- and polyarticular, resembles spondyloarthropathy more than it does rheumatoid arthritis

Table 4 Comparison of histological markers between SpA (PsA + AS + USpA) synovium and RA synovium

Marker	SpA (n = 50)	RA (n = 52)	P
Lining layer thickness	1.0 (1.0–2.5)	2.0 (0–3.0)	0.006
Vascularity	2.0 (1.0–3.0)	1.5 (1.0–3.0)	<0.001
Cellular infiltration	1.5 (0–3.0)	2.0 (0–3.0)	0.120
Lymphoid follicles	0 (0–3.0)	0 (0–3.0)	0.232
Plasma cells	0.5 (0–3.0)	0.5 (0–3.0)	0.497
Polymorphonuclear cells	0 (0–3.0)	0 (0–2.5)	0.008
CD3	1.5 (0–3.0)	2.0 (0–3.0)	0.152
CD4	1.0 (0–3.0)	1.0 (0–3.0)	0.192
CD8	1.0 (0–3.0)	1.5 (0–3.0)	0.737
CD20	1.0 (0–3.0)	2.0 (0–3.0)	0.231
CD38	1.5 (0–3.0)	2.0 (0–3.0)	0.060
CD138	1.0 (0–3.0)	2.0 (0–3.0)	0.447
CD68 lining	1.0 (0–3.0)	1.0 (0–3.0)	0.631
CD68 sublining	1.5 (0–3.0)	1.5 (0.5–3.0)	0.957
CD163 lining	2.0 (0–3.0)	1.5 (0–3.0)	0.033
CD163 sublining	1.5 (0–3.0)	1.0 (0–2.5)	0.031
CD1a	0 (0–3.0)	1.0 (0–3.0)	0.121
CD83	0 (0–1.0)	0 (0–3.0)	0.006
CD146	2.0 (0–3.0)	0 (0–3.0)	0.075
α_Vβ₃ lining	1.0 (0–3.0)	1.0 (0–3.0)	0.397
α_Vβ₃ sublining	1.0 (0–3.0)	1.0 (0–3.0)	0.306
E-selectin blood vessels	1.0 (0–3.0)	1.5 (0–3.0)	0.760
ICAM-1 lining	3.0 (1.0–3.0)	2.5 (0–3.0)	0.025
ICAM-1 sublining	2.0 (0–3.0)	2.0 (0–3.0)	0.654
ICAM-1 blood vessels	2.5 (0.5–3.0)	2.5 (0–3.0)	0.652
VCAM-1 lining	3.0 (0–3.0)	3.0 (0–3.0)	0.077
VCAM-1 sublining	1.5 (0–3.0)	1.5 (0–3.0)	0.473
VCAM-1 blood vessels	1.0 (0–3.0)	1.5 (0–3.0)	0.997
Intracellular citrullinated proteins	0%	44%	<0.001
Mab-12A	0%	46%	<0.001

The Mann–Whitney U-test was used to evaluate markers scored semiquantitatively, and the χ² test was used to evaluate markers scored as present or absent. Results are expressed as median (range), and markers evaluated as present or absent are expressed as percentage of positive results. P < 0.05 was considered statistically significant. AS, ankylosing spondylitis; ICAM, intercellular adhesion molecule; PsA, psoriatic arthritis; RA, rheumatoid arthritis; USpA, undifferentiated spondyloarthropathy; VCAM, vascular cell adhesion molecule.

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