Erosive osteoarthritis, psoriatic arthritis and pseudogout; a casual association?

According to recent hypothesis, the inflammation has a pivotal role in the onset and progression of erosive hand osteoarthritis (EHOA), psoriatic arthritis (PsA) and chondrocalcinosis (CC)/pseudogout. Albeit, it has been recognised for years as an association between EHOA and radiographic evidence of CC, but there are few reports of coexistence of microcrystalline arthritis and PsA. This is the first report that described a clinical experience concerning two consecutive cases of patients presented with EHOA, PsA and pseudogout. Two Caucasian women of 71 and 85 years old with a history of OA and mild psoriasis are presented with tenderness and swelling of first interphalangeal (IP) and wrist joint, respectively. Arthrocentesis performed at the first IP and wrist joint, respectively, showed an inflammatory synovial fluid with presence of calcium pyrophosphate dehydrate crystals. X-rays of hands, feet and knees showed characteristic features of EHOA, PsA and CC. Furthermore, HLA typing evinces the presence of HLA C*06; DRB*01 07 and HLA C*07; DRB*01 *11 alleles, respectively, predisposing factors of these inflammatory diseases. The relationship between these aggressive rheumatic diseases along with their clinical, radiographic, laboratory and genetic features is discussed.