A 49-year-old man with psoriasis was referred for pain at both first metatarsophalangeal (MTP) joints that had first developed at 20 years of age. Examination revealed swelled big toes and severe psoriatic onychodystrophy, but no axial involvement. Rheumatoid factor, anti-cyclic citrullinated peptide and antinuclear antibodies were normal. HLA evaluation revealed B13, Cw6, and B27 antigens. Foot radiograph showed bilateral acroosteolysis of terminal …