Painless knee mass in a young adult: answer.

This document discusses a case of a painless knee mass in a young adult. The MRI showed a soft tissue lesion in the posterior recess of the knee, closely related to the anterior cruciate ligament. A provisional diagnosis of a complex ACL ganglion was made based on the MRI findings. However, an aspiration biopsy revealed a synovial sarcoma, a rare and aggressive soft tissue sarcoma. The document emphasizes the importance of histopathological analysis in cases of ganglion aspiration to avoid misdiagnosis. The management of synovial sarcoma involves surgical resection and, in some cases, radiotherapy or neoadjuvant chemoradiotherapy. [Extracted from the article]