A bump had appeared on the left cheek the day before admission to the pediatric ER. The parents reported a febrile illness the previous week. On checkup: soft, mobile, non-tender, swelling palpated at the left mandibular area, with no skin discoloration.

Ultrasonographic examination demonstrated a lobulated, septated lesion at the left mandibular angle showing a fluid-fluid level (hematocrit effect), compatible with a macrocystic lymphatic malformation (also known as cystic lymphangioma) with intralesional hemorrhage. A hemorrhage in an otherwise small, undetected lymphangioma, is a viable explanation for the abrupt appearance of the buccal swelling.

The child had the lesion surgically removed shortly thereafter.

It should be emphasized that although in this case, the full extent of the lesion was demonstrated, an MRI study should be ordered in any case where there is doubt as to whether the lesion extends deeper into the neck. This holds true for any lesion, of course.

Of note, for many authors, "lymphangioma" has fallen out of favor because the suffix -oma implies a neoplasm ^1,2.