Management of a mesenteric vascular tumor with sirolimus in a 7-year-old child: a case report

Vascular tumors originating from the mesentery of small intestine are rare. There is no consensus regarding the diagnosis and treatment of unresectable mesenteric vascular tumors. A 7-year-old female patient was referred to our institution because of recurrent abdominal pain. The laboratory results revealed only elevation of CRP (3.67 mg/dL) and D-dimer (9.1 μg/mL). A 79×65×114 mm well-circumscribed mass was identified in the small intestinal mesentery on radiological findings. The mass showed minimal contrast enhancement and the superior mesenteric vessels ran through it. A laparoscopic biopsy was performed using a coaxial needle system for an accurate diagnosis. No perioperative complications, including bleeding, were observed. The pathological diagnosis was a vascular tumor with a lymphatic phenotype that was positive for mTOR by immunohistopathological examination. Therefore, the patient was administered sirolimus, an oral mTOR inhibitor. The prescribed dose was 1 mg (1.14 mg/m2) per day. Both the pain score and analgesic usage decreased within one week, and the D-dimer level normalized after two months. Furthermore, MRI three months later showed that the tumor had shrunk significantly to 64×31×68 mm. The adverse events were only grade 1 oral mucositis and grade 1 otitis externa as adverse events. Laparoscopic biopsies using the coaxial needle system may be effective for diagnosing mesenteric vascular tumors. Furthermore, sirolimus seems to be an effective treatment modality for the tumors that are mTOR positive.