Transillumination of a Cystic Lymphatic Malformation

A four-week-old with a mass at the base of his neck. A four-week-old, full-term male infant presented with a mass at the base of his neck (Panel A). The growth of the lesion, evident since his birth after an uncomplicated pregnancy, had been commensurate with the growth of the infant. Physical examination revealed a soft, well-defined, nontender mass in the neck measuring 11 by 8 cm. No abnormality was noted in the overlying skin. Application of a light source to the mass revealed complete transillumination (Panel B), which is consistent with the diagnosis of a macrocystic lymphatic malformation. Macrocystic lymphatic malformations, also called cystic hygromas, occur most often at the base . . .