title: PEComa of the terminal ileum mesentery as a secondary tumour in an adult survivor of embryonal rhabdomyosarcoma.
abstract: Perivascular epithelioid cell tumours (pecomas) are rare mesenchymal tumours that are characterized by perivascular epithelioid cell differentiation and immunoreactivity to myogenic and melanocytic markers. These tumours can be classified as benign, uncertain malignant potential, or malignant. Because of the rarity of pecomas, their cause and clinical prognosis remain unclear. To the best of our knowledge, no reports in the literature describe a pecoma of the terminal ileum mesentery as a secondary tumour in an adult survivor of childhood embryonal rhabdomyosarcoma, let alone any childhood cancer. Here, we present the case of a 27-year-old man with a pecoma involving the mesentery of the terminal ileum. At the age of 5, he had been treated with a combination of chemotherapy and high-dose pelvic radiation therapy for embryonal rhabdomyosarcoma, most likely arising from the posterior bladder wall. During routine follow-up 22 years after this patient's initial treatment, computed tomography imaging revealed a mass within the terminal ileum mesentery. The tumour was successfully treated with surgical resection, and pathology examination determined the mass to be a pecoma with uncertain malignant potential. This first case of a pecoma of the terminal ileum mesentery arising within a high-dose radiation therapy field as a secondary tumour in an adult survivor of childhood cancer highlights the importance of screening and surveillance in high-risk childhood cancer survivors treated with high-dose radiation therapy. Further research to build a better understanding of this remarkably rare tumour is warranted.
authors.affiliation: Department of Radiation Oncology, BC Cancer Agency-Vancouver Centre, Vancouver, BC; ; Pediatric Oncology Group of Ontario, Toronto, ON;
authors.forename: H
authors.initials: H
authors.lastname: Hasan
authors.affiliation: Department of Radiation Oncology, BC Cancer Agency-Vancouver Centre, Vancouver, BC; ; School of Population and Public Health, University of British Columbia, Vancouver, BC;
authors.forename: A F
authors.initials: AF
authors.lastname: Howard
authors.affiliation: Department of Pathology and Laboratory Medicine, Vancouver General Hospital, Vancouver, BC;
authors.forename: A H
authors.initials: AH
authors.lastname: Alassiri
authors.affiliation: Department of Anatomical Pathology, Vancouver General Hospital, Vancouver, BC;
authors.forename: T L
authors.initials: TL
authors.lastname: Ng
authors.affiliation: Division of Surgical Oncology, BC Cancer Agency, Vancouver, BC; ; Division of Surgical Oncology, Vancouver General Hospital, Vancouver, BC; ; Division of General Surgery, University of British Columbia, Vancouver, BC;
authors.forename: G
authors.initials: G
authors.lastname: McGregor
authors.affiliation: Department of Radiation Oncology, BC Cancer Agency-Vancouver Centre, Vancouver, BC; ; Department of Surgery, University of British Columbia, Vancouver, BC.
authors.forename: K
authors.initials: K
authors.lastname: Goddard
keywords: childhood cancer; pecoma; radiation therapy; rhabdomyosarcoma; secondary neoplasms; terminal ileum mesentery