A unique case of the rapid onset of a large cystic hygroma in the adult.

Cystic hygroma is an uncommon lymphatic tumor seen rarely in adults, with less than 100 cases reported in the literature. The etiology and pathophysiology of this lesion is still in question. The majority of cystic hygromas occur in the head and neck, particularly in the posterior triangle. Although cystic hygromas tend to enlarge progressively over a span of weeks or months, relatively rapid enlargement over a span of days has been described. We present the unique case of an adult woman who experienced sudden onset of a large cystic hygroma in the neck without history of antecedent swelling, infection, or trauma. Successful surgical removal of the hygroma was performed. A brief review of the literature is presented.