Malignant solitary tumor in a child: a case report and review of the literature.

Solitary fibrous tumor in the mesentery is rare. We report a case of a malignant solitary fibrous tumor in the appendical mesentery of 6-year-old boy. Computed tomography and ultrasound of the abdomen demonstrated a well-defined solid mass, 4.0 cm in diameter, in the lower right abdomen. At laparotomy, an encapsulated tumor was observed in the appendical mesentery and was easily separated from the appendix. Immunohistochemistry stain showed that the spindle-shaped cells were positive for CD34 and neuron-specific enolase. DOG-1, CD117, desmin, S-100 protein, and SMA were negative. The sequence of KIT and platelet-derived growth factor receptor α was presented with wild type, no mutation. The patient received the reoperation 5 months postoperation. Despite these treatments, the relapsed tumor rapidly and markedly enlarged. The patient died of recurrent tumor with liver dissemination 7 months after reoperation.