In about 20% of patients with psoriatic arthritis (PsA) the rheumatological manifestations precede the onset of the cutaneous lesions. If there is a family history of psoriasis these patients are diagnosed as having psoriatic arthritis sine psoriasis. In the past, they were also classified among patients with undifferentiated spondyloarthritis. The clinical spectrum of PsA sine psoriasis is wide and identified by dactylitis and/or distal interphalangeal arthritis, HLA-Cw6, and a family history of psoriasis. The ClASiffication of Psoriatic ARthritis (CASPAR) criteria of PsA include PsA sine psoriasis.