Abstract
An adolescent female patient presented with atraumatic left knee pain and limited flexion. MRI demonstrated evidence of a soft tissue lesion abutting the posterior cruciate ligament. Differential diagnosis included pigmented villonodular synovitis (PVNS) and fibroma of the tendon sheath (FTS). Following arthroscopic biopsy, histopathological evaluation confirmed FTS. The tumour was then excised via an arthroscopic approach. This case report provides a unique example of FTS abutting the cruciate ligaments in an uncommonly young female patient. It highlights the importance of including benign processes, such as FTS, in the differential with more aggressive-type diagnoses like PVNS. Furthermore, this case exemplifies an appropriate surgical indication for FTS. Finally, it emphasises the importance of communication and collaboration among orthopaedic subspecialists in providing safe and effective arthroscopic treatment of this unique tumour presentation.