Plexiform fibromyxoma: report of two pediatric cases and review of the literature.

Plexiform fibromyxoma is a distinctive mesenchymal neoplasm usually arising in the gastric antrum. We report 2 cases of this entity in pediatric patients, including the first case arising in the esophagus. The patients were a 16-year-old female who presented with chest pain and was found on computed tomographic scan to have a midesophageal mass at the level of the carina, and an 11-year-old female with a gastric mass. Both patients underwent surgical resection of their tumors, which histologically exhibited a plexiform growth pattern with multiple nodules in the muscularis propria and infiltrative borders. The nodules were composed of a rich myxoid stroma with bland uniform spindle cells, no mitoses or necrosis, and delicate blood vessels in the background. Immunohistochemical studies demonstrated that the tumor cells were immunoreactive with smooth muscle actin and not reactive with S-100, CD34, desmin, and c-kit (CD117). We report the first case of plexiform fibromyxoma originating in the esophagus, emphasize its occurrence in pediatric patients, and review the related literature.