Infratemporal inflammatory myofibroblastic tumour with orbital extension

Inflammatory myofibroblastic tumour (IMT) is a rare distinctive neoplasm of intermediate biological potential with a predilection for the abdominopelvic region and lung of children and young adults. It is histologically composed of spindle cells (myofibroblasts) in a myxoid to collagenous stroma with a prominent inflammatory infiltrate composed primarily of plasma cells and lymphocytes. Its pathogenesis is controversial. Arising most commonly in the lungs, only two cases of histopathologically confirmed IMT originating from the infratemporal and pterygopalatine fossae have been documented in the literature. Neither had orbital involvement. We now report the first case of IMT originating from the infratemporal fossa with orbital extension in a previously well 31‐year‐old woman. The patient presented with a 5‐month history of intermittent right‐sided headaches, progressive trismus and right lower lid swelling. She then developed right proptosis, diplopia and paraesthesia in the ophthalmic and maxillary divisions of her trigeminal nerve. Magnetic resonance imaging showed a soft tissue mass occupying most of the right infratemporal fossa with extension into pterygopalatine fossa and orbit. Provisional diagnosis from an open biopsy was nodular fasciitis. She underwent surgical debulking of the infratemporal fossa and lateral orbit through a coronal and trans‐oral approach with trans‐zygomatic access via total zygomatic osteotomy. Review of intraoperative specimens revised the diagnosis to IMT. Further management included systemic corticosteroids and adjuvant radiotherapy.