Racial differences in mycosis fungoides: A retrospective study with a focus on eosinophilia

Background: Mycosis fungoides (MF) is often associated with eosinophilia and portends a poorer prognosis. MF is more common in blacks and follows a more aggressive course compared with whites. Objective: We further elucidate racial differences between blacks and whites with MF, focusing on blood eosinophilia. Methods: The records of 345 patients with MF were reviewed for demographic, clinical, and pathologic data and evaluated by analysis of variance. Results: The average age at diagnosis for blacks was 45 years and was 55 years for white patients (P <.001). In the cohorts of patients with and without blood eosinophilia, the average maximum blood eosinophil count had a greater range in blacks. Independent of race, blood eosinophilia was predictive of more advanced disease (P <.0001), increased number of treatment types (P <.002), and less responsiveness to treatment (P <.0006). Limitations: This was a retrospective study at a single institution. Conclusions: These differences observed in eosinophil values may highlight disparities in MF diagnosis or a difference in pathophysiology between races.