Longitudinal bronchoscopy findings in children with mucopolysaccharidosis II (MPS II)

Abstract

Background: Hunter syndrome or MPS II is a X-linked lysosomal storage disease with significant respiratory involvement leading to obstruction of large airways due to “MPS” deposits and remodeling. We had shown significant airway involvement and need for bronchoscopy assisted intubation in patients with MPS prior to wide spread use/approval of enzyme replacement therapy (ERT) [Muhlebach, Ped Pulm 2013]. Aim: To review progression of airway findings in patients with severe form of MPS II with early ERT. Methods 20 patients with severe form of MPS II underwent yearly bronchoscopies (bronch) as part of research evaluations in a phase 2/3 trial of intrathecal ERT. Results: Systemic ERT, required to enlist in intrathecal ERT trial, had been started at median (range) age of 3.9 years (0.1-4.8). Median age of 1st bronch was 4.3 years (2.4-9.7) median (range) time of follow-up and number of bronchs were 4.7 years (2-9) and 5 (2-9), respectively. MPS specific upper airway findings were present in all patients even at initial bronch and showed progression from adenoidal enlargement, pharyngeal deposits and –malacia to the lower airways with initial tracheal flattening and later MPS tracheopathy characterized by tracheal wall instability and tortious trachea with bronchitis at this stage. Comparison to 15 patients of similar ages from pre-ERT time period, including those with mild MPS II, showed no clear difference in airway involvement. Conclusion: Despite early use of ERT airway disease in the severe form of MPS II progresses from upper to lower airway with severe tracheopathy occurring in teenagers and adults. Thus ongoing careful management of airway and pulmonary disease in MPS remains indicated.