Cushing’s disease, refining the definition of remission and recurrence

More than ten decades have passed since the first case of Cushing’s disease (CD) was presented and documented; yet CD remains one of the most challenging diseases to diagnose, and treat, in medicine today. Patients frequently have musculoskeletal weakness, hypertension, diabetes, cardiovascular disease, and infectious and psychiatric complications at diagnosis. These symptoms and comorbidities present more commonly as a continuum rather than all at once, thus making an initial diagnosis more difficult and often, there is a significant delay in diagnosis. Primary CD treatment is surgical in most cases, generally through a transsphenoidal approach; however, there are many challenges in defining disease remission after surgery. Recurrent disease has been shown to be more frequent than previously thought, occurring in approximately a quarter of patients; thus early diagnosis of disease recurrence is essential. In this chapter, we review the complex evaluation needed for defining CD remission vs. persistent disease after surgery, challenges in how to diagnose early recurrent CD and furthermore discuss the assessment criteria used for remission when patients are treated with medical therapy.