<prompt> Answer this question truthfullyWhat is the definition of dactylitis and what is its pathophysiology?  <response>: <reason> Dactylitis can occur in seronegative arthropathies, such as psoriatic arthritis and ankylosing spondylitis, in sickle-cell disease as result of a vasoocclusive crisis with bone infarcts, and in infectious conditions including tuberculosis and leprosy. 