Rebound adenoid hyperplasia after chemotherapy in pediatric patients with head and neck lymphoma: MR imaging findings

To assess MR imaging findings of rebound adenoid hyperplasia after chemotherapy in pediatric patients with head and neck lymphoma. Eight pediatric patients with head and neck lymphoma treated with chemotherapy alone or concurrent chemoradiotherapy were included. All patients underwent pre-therapeutic assessment and post-therapeutic follow-up by MR imaging. The maximum thickness of the adenoid was assessed on transverse T2-weighted images. Rebound adenoid hyperplasia was defined as more than half of the pre-therapeutic thickness after severe atrophy. The pre-therapeutic maximum thickness of the adenoid ranged from 10 to 18 mm (mean, 15 mm). In all patients, the thickness of the adenoid dramatically decreased (mean 1 mm) within 1 year after the cessation of chemotherapy. On follow-up MR imaging, rebound adenoid hyperplasia was observed in five patients (63 %). Re-atrophy following rebound adenoid hyperplasia was observed in two patients (25 %), and no re-atrophy was observed in three patients (37 %). Rebound adenoid hyperplasia was not observed in three patients (37 %) who were in their late teens, and who had been treated with concurrent chemoradiotherapy. Rebound adenoid hyperplasia was often observed after chemotherapy in pediatric patients with lymphoma. MR imaging was useful for the assessment of rebound adenoid hyperplasia.