A 32-year-old woman with ulcerative colitis (UC) of 8 years' duration presents with bloody diarrhea and abdominal cramping. She is on mesalamine and azathioprine. Colonoscopy shows continuous mucosal inflammation limited to the colon with crypt distortion and surface ulceration. Regarding the extraintestinal manifestations (EIMs) of UC, all of the following are associated with disease activity EXCEPT: