A Veiled Lymphatic Malformation: Stridor in a Child.

Lymphatic malformation (LM) is a congenital lymphatic dysplasia associated with the p110α subunit of PI3K (PIK3CA) mutation. A two-year-old boy presented with a history of noisy breathing from the age of two months, which was progressively worsening. Inspiratory stridor was audible with subcostal recession. Flexible nasopharyngolaryngoscopy (FNPLS) revealed an enlarged right arytenoid. Other supraglottic structures were normal, and bilateral vocal cords were mobile. Direct laryngoscopy showed that the right arytenoid was enlarged with a smooth surface. On the subsequent visit, there was a painless soft lateral neck swelling, 4 cm x 4 cm in size, with normal skin. MRI confirmed LM with the predominantly macro-cystic component, involving primarily the right neck and upper mediastinum, causing airway compression. Sirolimus therapy was initiated, and at one month of follow-up after the treatment, his stridor had improved. The incidence of stridor secondary to head and neck tumors such as teratomas, hemangiomas, and LM accounts for less than 3%. The typical manifestation of LM often involves a painless, soft, and compressible mass that progressively increases in size. Features of macrocystic LM on MRI are multilocular and hyperintense cystic mass on T2-weighted imaging. The treatment methods for LM include surgical and non-surgical options. Despite being an off-label application, the response rate of sirolimus therapy in children with LM is reported to be 91%, and the first clinical response was observed in less than three weeks. Stridor is frequently encountered in children but rarely due to head and neck tumors. However, as in our case, a large LM may cause recurrent airway obstruction, and the neck swelling may appear later. Atypical airway findings, especially endoscopic examination, in a child with stridor should be complemented with imaging to examine the possibility of extra-laryngeal mass or external compression.