The Nonradiographic Axial Spondyloarthritis, the Radiographic Axial Spondyloarthritis, and Ankylosing Spondylitis: The Tangled Skein of Rheumatology

Figure 1

The circles “A,” “B,” and “C” represent (1) the axial spondyloarthritis (axSpA); (2) the peripheral SpA, and (3) the extra-articular manifestations of SpA, respectively. Within the axSpA (circle A) the two subcomponents are “Aa” and “Ab” that represent nonradiographic axSpA (nr-axSpA) and radiographic axSpA (r-axSpA), respectively. Circles “B,” “C,” “D,” “E,” and “F” represent (i) peripheral arthritis of SpA pattern, (ii) extra-articular features, (iii) inflammatory bowel disease-related SpA, (iv) psoriasis-related SpA, and (v) reactive arthritis-related SpA. Patients in circle “A” are often identified as “primary” SpA and those in circles “C,” “D,” or “E” as “secondary” SpA.