Infections complicating mycosis fungoides and Sézary syndrome.

To determine, in patients with mycosis fungoides and Sézary syndrome, the incidence of infections, the importance of nosocomial infections, and the epidemiologic factors associated with cutaneous and visceral infections. Retrospective inception cohort study at a university medical center referral clinic. Three hundred fifty-six patients with mycosis fungoides or Sézary syndrome. Incidence rates for specific infections, and multivariate risk ratios for demographic and clinical factors associated with infection. Cutaneous bacterial infection was most common (17.0 infections per 100 patient-years), followed by cutaneous herpes simplex virus and herpes zoster virus infection (3.8 infections per 100 patient-years), bacteremia (2.1 infections per 100 patient-years), bacterial pneumonia (1.7 infections per 100 patient-years), and urinary tract infection (1.4 infections per 100 patient-years). Twenty-seven percent of herpesvirus infections disseminated on the skin but none disseminated to internal organs. Pneumonia or bacteremia was present in 88% of patients who died of infection. Only three patients had invasive fungal or protozoal infection. Nosocomial infections accounted for 19% of cutaneous bacterial infections, 59% of bacteremias, 62% of pneumonias, and 88% of infections leading to death. By logistic and Cox regression, the presence of extracutaneous involvement with lymphoma was the most important independent risk factor for recurrent bacterial skin infection (risk ratio [RR], 12; 95% confidence interval [CI], 1.2 to 120), disseminated herpesvirus infection (RR, 28; 95% CI, 2.7 to 290), bloodstream infection (RR, 5.5; 95% CI, 1.7 to 18), and death from infection (RR, 15; 95% CI, 3.6 to 64). Community-acquired bacterial skin infections are a common cause of morbidity in patients with mycosis fungoides and Sézary syndrome but are usually treated without hospital admission. Bacteremia and pneumonia, which are usually nosocomial, are the major infectious causes of death. Advanced disease stage, independent of corticosteroids and other therapies, is the most important risk factor for both cutaneous and systemic infections.