A 44-year-old electrician with a 12-year history of chronic plaque psoriasis presents with worsening nail changes and new-onset joint pain in the distal interphalangeal joints. On examination, all ten fingernails show a mixed nail dystrophy. The structure marked **A** in the diagram—deep irregular nail pits—is a hallmark of nail psoriasis and distinguishes it from other causes of nail pitting. Which of the following clinical features would BEST support the diagnosis of psoriatic arthritis in this patient with these nail findings?