A Case of Congenital Infantile Fibrosarcoma of Sigmoid Colon Manifesting as Pneumoperitoneum in a Newborn
A 2-day-old Korean boy, delivered at 37 weeks by cesarean section owing to fetal bradycardia, with a birth weight of 3,420 g, was referred to the neonatal intensive care unit in Pusan National University Children's Hospital because of abdominal distension and free air in the peritoneal cavity at May 1st, 2011. He experienced normal passage of meconium on the first day of life. A plain abdominal radiograph showed normal air-filled loops of bowel; however a large amount of free air occupied the central portion of the abdomen (). The patient underwent an emergency laparotomy on the day of admission to the neonatal intensive care unit. A large amount of bile-stained, turbid fluid was encountered upon entry into the peritoneal cavity. A round mass, about 5 cm in diameter, was observed in the left lower abdominal cavity, and it seemed to wrap around a loop of sigmoid colon (). No dilatation of the colon proximal to the lesion was found. Segmental resection of the sigmoid colon, including the mass, was performed. Grossly, there was no definite perforation site visible on the colonic surface. No lymph node enlargement or other pathological findings were found during surgery. The patient was discharged on postoperative day 10 without any complications. Pathologic analysis report described an infantile fibrosarcoma, measuring about 4.7 × 2.8 cm, involving mainly the submucosa and muscularis propria with an infiltrative growth pattern (). The mitotic count was 12/10 high-power fields. The immunohistochemical stain of the tumor was positive for vimentin and SMA, and negative for h-caldesmon, S-100, CD34, c-kit, desmin, and ALK-1 (). The Ki-67 proliferation index was 20%. Because complete surgical resection was performed and the surgical resection margins were free tumor, the patient was observed without adjuvant therapy. Radiologic evaluation showed no evidence of tumor recurrence 12 months postoperatively ().