Recurrent infantile inflammatory myofibroblastic tumor of mesentery--Case report and review of imaging findings.

Inflammatory myofibroblastic tumors (IMT) are rare soft tissue tumors of intermediate malignant potential with tendency for local recurrence. Although they can occur at all age groups, occurrence in infants is extremely unusual and their imaging characteristics are not well described. A 3-month-old female infant presented with gradually progressive abdominal distention without any fever or weight loss. She had a large ill-defined homogenous hypodense lesion of size 8.4 × 11.4 × 11.3 cm (APxTraxSag) in the abdomen showing mild delayed post contrast enhancement. She underwent exploratory laparotomy with gross total excision of mesenteric mass, histopathology of which was suggestive of IMT. She had recurrence within 6 months of complete resection with a well-defined heterogeneously enhancing lesion of size 1.8 × 1.8 × 2.3cm (APxTraxSag) in right paravesical region abutting the bladder without invasion with a similar lesion of size 4.4 × 2.1 × 3 cm (APxTraxSag) in left subdiaphragmatic region abutting superior surface of spleen (no invasion). Since, surgery in our patient would have entailed splenectomy and partial cystectomy, systemic therapy with ceritinib (anaplastic lymphoma kinase [ALK] inhibitor) was planned for her with which she had a near complete response after 2 months. A high index of suspicion is required to differentiate IMT from other common causes of mesenteric masses in children and role of radiologist is quintessential in this regard. Local recurrence with abutment but without invasion of surrounding structures points to the intermediate malignant pathology of IMT and may provide a clue to diagnosis. Systemic therapy is effective in patients who are ALK positive and destructive surgery should be avoided.