Reply to letter by Priori et al commenting on whether Behçet's syndrome patients with acne and arthritis comprise a true subset

The papulopustular lesion/arthritis cluster of Behcet's syndrome also clusters in families

“…Our previous studies on pustular lesions and their association with joint involvement in BS have shown that the pustular lesions of BS are not sterile [25], enthesopathy can also accompany this association [8], and HLA-B27 positivity and sacroiliitis are infrequent among these patients [26]. Our observations suggest that the association of pustular lesions and joint involvement in BS is quite similar to acne-associated ReA.…”

Behçet’s syndrome: Facts and controversies

“…A recent study has shown that the frequency of HLA B-27 and sacroiliitis was not increased in these patients. 58 These studies support the hypothesis that patients with Behçet's syndrome and arthritis and acne form a distinct cluster and this cluster has recently been shown in familial cases as well. 59 Synovial fluid is commonly inflammatory, but a good mucin clot is usual.…”

Musculoskeletal manifestations in children with Behçet’s syndrome: data from the AIDA Network Behçet’s Syndrome Registry

“…The occurrence of spondyloarthritis in BS deserves separate consideration. The Turkish colleagues observed a higher ultrasound enthesopathy score in adult BS patients with acne and arthritis compared to other BS patients as well as patients with rheumatoid arthritis and healthy controls; on the other hand, they found neither radiographic sacroiliitis, nor HLA B27 association in this BS cluster, questioning the hypothesis that BS belongs to the spondyloarthropathy group [ 13 , 27 , 28 ]. This is not the case in the present study, as sacroiliac inflammation was detected in 7/37 subjects at disease onset and appeared later in the clinical history of 4 additional patients, resulting in axial involvement in almost 1/3 of the cohort, although HLA B27 was absent in all cases.…”