Inflammatory myofibroblastic tumor: clinical, morphological, immunohistochemical and molecular features of a pediatric case.

Inflammatory myofibroblastic tumor is an uncommon tumor regarded as "intermediate malignancy". We present the clinical, pathological and molecular features of a mesenteric inflammatory myofibroblastic tumor in a 9-month-old male infant. The patient was referred to Anna Meyer Children Hospital of Florence, Italy, for an asymptomatic abdominal mass measuring about 7cm. The lesion was radically excised, and the postoperative course was uneventful. Histologically, the tumor was composed of spindle cells immunopositive for vimentin and desmin admixed with an inflammatory infiltrate. Rearrangement of ALK gene was demonstrated by FISH and immunohistochemistry (cytoplasmic, perinuclear and punctate immunocoloration). The peculiar punctate ALK immunocoloration suggested a possible unusual ALK gene rearrangement involving the CLTC gene.