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.
Highlights
Multimodal therapy has resulted in improved long-term survival for children diagnosed with rhabdomyosarcoma, childhood rhabdomyosarcoma survivors are at an increased risk of developing secondary neoplasms[1]
Secondary neoplasms arising in a high-dose rt field are a well-known complication of childhood cancer[3], the present report concerns the first case of a perivascular epithelioid cell tumour of the terminal ileum mesentery arising 22 years after treatment as a secondary neoplasm within a high-dose rt field in an adult survivor of embryonal rhabdomyosarcoma
4 cycles of chemotherapy, pelvic exenteration, and intraoperative radiation with no evidence of recurrence. His pecoma was successfully treated with surgical resection, and immunohistochemistry showed that the tumour cells were positive for melanocytic marker HMB-45
Summary
Multimodal therapy has resulted in improved long-term survival for children diagnosed with rhabdomyosarcoma, childhood rhabdomyosarcoma survivors are at an increased risk of developing secondary neoplasms[1]. Secondary neoplasms arising in a high-dose rt field are a well-known complication of childhood cancer[3], the present report concerns the first case of a perivascular epithelioid cell tumour (pecoma) of the terminal ileum mesentery arising 22 years after treatment as a secondary neoplasm within a high-dose rt field in an adult survivor of embryonal rhabdomyosarcoma. Based on that classification scheme, the presence of nuclear pleomorphism or multinucleated giant cells and a mitotic rate exceeding 1 in 50 high-power fields led to a final diagnosis of pecoma with uncertain malignant potential in this case. Pecomas can be classified as benign, but can have aggressive clinical behavior, with the opposite being true for malignant pecomas[13]
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