Impact of Preoperative Systemic Corticosteroids on the Histology and Diagnosis of Eosinophilic Chronic Rhinosinusitis

<b><i>Background:</i></b> The histological changes corticosteroids induce in nasal polyps, and whether these changes have an impact on the diagnosis of eosinophilic chronic rhinosinusitis (ECRS), currently remain unclear. <b><i>Objectives:</i></b> A prospective controlled multicenter trial was conducted to evaluate the efficacy of the low-dose and short-term oral prednisolone (oPSL) treatment for tissue eosinophil infiltrations in ECRS. <b><i>Methods:</i></b> Subjects with ECRS diagnosed by previous biopsies received a low dose of oPSL for 3 days (PSL 3) or 7 days (PSL 7) before surgery. Changes in the tissue eosinophil count after these treatments were evaluated. Furthermore, the percent change of tissue eosinophil count from baseline and its impact on the diagnosis defined by the JESREC study were examined. <b><i>Results:</i></b> There were 23 and 21 subjects in the PSL 3 and PSL 7 groups, respectively. Polyp scores, clinical symptom scores, and the proportion of blood eosinophils significantly decreased after the treatment, and no significant differences were observed between the groups. The entire tissue eosinophil count tended to be slightly decreased in both groups without reaching a statistically significant value. The median percent change of tissue eo­sinophil count from baseline was 83.6%, and only the posttreatment proportion of blood eosinophil showed a mild correlation with it. Seven out of 44 nasal polyp specimens collected from the superficial part of the middle meatus showed &#x3c; 70 eosinophils/high-power field; therefore, the false negative rate was 15.9%, but decreased to 11.4% when other parts were included in the histological evaluation. <b><i>Conclusions:</i></b> Low-dose and short-term oPSL did not appear to markedly affect the tissue eosinophil count in ECRS patients; however, the potential for misdiagnoses due to the effects of oPSL cannot be rejected. The diagnosis of ECRS prior to the administration of corticosteroids or tissue evaluations using multiple tissue parts is desirable.