Inflammatory myofibroblastic tumour at the pacemaker site

Abstract

Inflammatory myofibroblastic tumour (IMT) or inflammatory pseudotumour is a histologically distinctive lesion occurring primarily in the viscera and soft tissue of children and young adults. We report an unusual case of IMT which had undergone malignant transformation in the chest wall at the pacemaker site. A 64-year-old male presented with a history of high fever, loss of appetite and weight loss of three months duration. He had a dual chamber pacemaker reinserted in the left infraclavicular region in the previous year. This was followed by a gradually enlarging hard swelling at the insertion site. The CT-scan showed a soft tissue mass encasing the pacing box, without intrathoracic extension. The trucut biopsy was suspicious of soft tissue sarcoma. A well encapsulated hard mass, with pacemaker embedded within it was resected en-bloc ensuring wide resection margins. Histology revealed fascicles of spindle cell proliferation with prominent inflammatory component, occasional spindle cells with prominent nucleoli and scattered atypical mitotic figures, with areas of focal necrosis. The lesional cells were negative for CD21, smooth muscle actin, ckit, cytokeratins and anaplastic lymphoma kinase 1. A diagnosis of IMT with malignant transformation i.e. inflammatory fibrosarcoma was made. He had adjuvant radiotherapy and uneventful recovery.