Improvement in Pituitary Imaging After Targeted Therapy in Three Children with BRAF-Mutated Langerhans Cell Histiocytosis with Pituitary Involvement

Abstract

Langerhans cell histiocytosis (LCH) is a rare myeloid neoplasia in children. BRAF mutations are associated with permanent diabetes insipidus (DI). The onset of clinical DI is always latent with imaging evidence of pituitary involvement. In this study, we reported three children with BRAF-mutated LCH with pituitary involvement who improved after targeted therapy (dabrafenib and trametinib). The results may indicate that pituitary involvement may be reversible in some patients with LCH if it is observed and treated before clinical DI. Targeted therapy may be an effective choice for LCH patients with early pituitary involvement who were irresponsive to first-line or second-line chemotherapy. However, a relapse after targeted therapy is completed in patients with persistently positive cfBRAF ^V600E mutations is still a challenge that needs to be resolved. The timing of introducing targeted therapy, its appropriate duration and effective combinations with chemotherapy or other targeted drugs should be explored further.

Keywords: BRAF mutation; Langerhans cell histiocytosis; children; pituitary; targeted therapy.

Figure 1

Pituitary MRI (sagittal plane) in the three patients reported in this study. In case 1, (A) the bright-spot of posterior pituitary on T1WI was absent and (B) recurred after 3-month dabrafenib treatment (white arrowheads). In case 2, (C) the bright-spot of posterior pituitary was absent and (D) recurred after 1-month dabrafenib treatment (white arrowheads). In case 3, (E) decreased bright-spot of posterior pituitary on T1WI (white arrowhead) and infundibular thickening (red arrowhead) were observed. (F) After 1-month dabrafenib combined with trametinib treatment, the brightness was higher (white arrowhead) with recovered infundibulum (red arrowhead).