Huge pelvi-abdominal malignant inflammatory myofibroblastic tumor with rapid recurrence in a 14-year-old boy.

Inflammatory myofibroblastic tumor (IMT) is an uncommon benign neoplasm with locally aggressive behavior but malignant change is rare. We report an unusual case of pelvic-abdominal inflammatory myofibroblastic tumor with malignant transformation in a 14-year-old boy presenting with abdominal pain and 9 kg body weight loss in one month. Computed tomography revealed a huge pelvi-abdominal mass (30 cm), possibly originating from the pelvic extraperitoneal space, protruding into the abdomen leading to upward displacement of the bowel loops, downward displacement of the urinary bladder, massive central necrosis, a well-enhanced peripheral solid component with prominent peritumoral vascularity. Subsequent examination confirmed the computed tomographic findings. Histopathologic examination revealed proliferative epitheloid and spindle cells, inflammatory cell infiltration and high mitotic counts. Immunohistochemistry was strongly positive for anaplastic lymphoma kinase and revealed a high proliferative index (ki-67 = 40%). DNA sequencing and electronic microscopy further confirmed the primitive fibroblastic cell phenotype of the tumor and a final diagnosis of inflammatory myofibroblastic tumor with malignant transformation was established. Rapid tumor recurrence was noted 20 d after radical tumor resection. To our knowledge, this is the largest documented case of IMT in a pediatric patient and the first report of IMT with malignant transformation originating from the pelvic extraperitoneal space.

Multimodality treatment in the control of deep musculoaponeurotic fibromatosis.

BACKGROUND: Deep musculoaponeurotic fibromatoses are rare soft tissue neoplasms with a propensity for local recurrence. METHODS: A retrospective analysis was carried out of the factors contributing to local disease control in 75 patients treated between 1963 and 1993. RESULTS: Multivariate analysis identified the type of surgical excision (P < 0.001) and involvement of pathological resection margins (P < 0.02) as significant factors contributing to local recurrence. After a median follow up of 47 months (range 24 months to 29 years) 31 (49 per cent) of the 63 patients who had an 'adequate' surgical resection developed local recurrence. The median time before development of local recurrence was 83.4 (range 8-129) months in patients with clear pathological resection margins. This was significantly shortened to 13.1 (range 2-35) months in those with positive margins (P < 0.001). CONCLUSION: Adequate surgical extirpation is the most important determinant in local disease control. Treatment of local recurrence ranged from observation during periods of disease stabilization to multimodality treatment for aggressive disease.