• Inflammatory myofibroblastic tumour
• malignant transformation
• metastasis
• ALK amplification
• TPM3-ALK, gene amplification
• genetics
• soft tissue tumours

Inflammatory myofibroblastic tumour (IMT) is a distinctive neoplasm that occurs primarily in viscera and soft tissues, and predominantly affects children and young adults. Histologically, IMT is composed of a myofibroblastic spindle cell proliferation accompanied by a mixed inflammatory infiltrate.1 Several studies have shown that up to 30–50% of IMTs contain anaplastic lymphoma kinase (ALK) fusion genes.1–6 The neoplastic cells in IMT are generally uniform and bland. In rare conditions, the tumour may exhibit histological malignant transformation1 3 4 7; however, the molecular biology underlying this evolution is still poorly understood.

Herein, we report a case of a classic IMT that evolved into a high-grade malignant sarcoma with amplification of the TPM3-ALK fusion gene.

A 29-year-old man presented with a history of multiple episodes of abdominal pain for 1 year. An abdominal computed tomography (CT) scan revealed a large left upper quadrant abdominal mass associated with liver lesions. He underwent a subtotal resection of the mesenteric tumour; however, the liver lesions were only biopsied. He received ifosfamide and adriamycin for two complete courses of chemotherapy without response. The patient died of the disease 4 months following the surgery.

Macroscopic inspection revealed a 15.8×15.0×8.2 cm bosselated multinodular mass in the mesentery with transmural involvement of colonic wall. Additionally, multiple omental implants were also present. On sectioning, the mass had a firm pink grey fleshy cut surface …