AUTHOR=Zhang Yongbai , Huang Wenpeng , Li Liming , Qiu Yongkang , Jiao Hao , Chen Zhao , Yang Qi , Song Lele , Kang Lei 

TITLE=Retroperitoneal alveolar rhabdomyosarcoma intruding into spinal canal: A case report and literature review

JOURNAL=Frontiers in Medicine

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.1019964

DOI=10.3389/fmed.2022.1019964

ISSN=2296-858X

ABSTRACT=Background： Rhabdomyosarcoma (RMS) is the most frequent soft sarcoma in children and adolescents. Alveolar rhabdomyosarcoma (ARMS) is a relatively rare subtype characterized by aggressive behavior and unsatisfactory prognosis. ARMS can arise anywhere but most commonly occurs at extremity sites with an extremely small fraction in the retroperitoneum. The utility of 2-Deoxy-2-[fluorine-18]-fluoro-D-glucose (18F-FDG) positron emission tomography combined with computed tomography (PET/CT) remains to be established in ARMS.
Case Report： A 3-year-old female was accidentally found with a large left upper abdominal mass for a day. Computed tomography (CT) examination indicated a huge soft tissue mass in the left retroperitoneum extending superiorly to the level of the left hilus renalis and inferiorly to the left acetabulum in the pelvic cavity, with intrusion into the lumbar foramens. 18F-FDG PET/CT found a mass in the left retroperitoneum from the level of T12 to the left acetabulum, with the maximum standardized uptake value (SUVmax) of about 7.0 and CT value of about 39 HU, invading the left L3-5 intervertebral foramina and protruding into the spinal canal, with unclear boundary with the spinal cord. Retroperitoneal tumor resection and vascular exploration repair operation were performed. Postoperative biopsy, immunohistochemical staining, and genetic detection with FKHR rupture confirmed an ARMS. The patient received chemotherapy and was in a good condition with no recurrence and obvious complications.
Conclusion： Retroperitoneal ARMS is rare and indicates a poor outcome with the potential to involve vital organs and intrude into the spinal canal. Accurate diagnosis and staging using PET/CT would contribute to better risk stratifications and individually appropriate treatment.