Complaints of limited stretching of the knee. No past history of trauma.
A 46-year-old male presented with complaints of limited stretching of his knee. The patient’s history revealed no trauma in the past. MRI of the right knee was performed. On a subsequent arthroscopy, a solid intra-articular fibrous tumor was found and completely removed. Histological examination revealed giant cell tumor of the tendon sheath.
Giant cell tumor of the tendon sheath (GCTTS), also called nodular tenosynovitis, is a benign tumor, which occurs in the tendon sheath of the digits or in joints of the extremities. Histologically the tumor consists of proliferation of hystiocytes, multinuclear giant cells, lipid laden macrophages (foam cells) and hemosiderin-laden cells. Owing to the presence of hemosiderin deposition and dense acellular fibrous tissue, low signal intensity within the lesion on both T1- and T2-weighted spin echo MR images is seen. This pattern however is variable and regions of high signal intensity on T2-weighted spin echo MR images may be seen. Because of the variable amount of hemosiderin in GCTTS the tumor shows a lower signal intensity than that of skeletal muscle on T2-weighted and gradient-echo MR images. The differential diagnosis includes pigmented villonodular synovitis and intra-articular ganglion cyst. Pigmented villonodular synovitis shows the same signal intensity as GCTTS on T1- and T2-weighted spin echo MR images, but usually has a more extensive intra-articular involvement with typical frondlike villous masses. It is mostly inhomogeneous and enhances markedly after gadolinium injection. An intra-articular ganglion cyst contains fluid and has always a homogeneous high signal intensity on T2-weighted spin echo MR images, and low to intermediate signal intensity on T1-weighted spin echo MR images.
Giant cell tumor of the tendon sheath (GCTTS)
Based on the provided MRI images of the knee joint, a localized soft tissue mass can be seen in the joint cavity or around the tendon sheath. This mass shows overall low signal intensity on T1-weighted and T2-weighted images, exhibiting signal intensity that is lower or similar compared to the adjacent skeletal muscle (especially on T2-weighted and gradient echo sequences). Certain areas may show slightly higher signal, suggesting localized tissue components or a small amount of fluid or fibrous content within. No obvious bony destruction is noted, and the adjacent trabecular structure remains relatively intact. There are no significant signs of erosion or destruction on the articular cartilage surface, and no obvious synovial thickening or large-scale joint effusion is observed.
Considering the patient is a middle-aged male with no significant history of trauma, clinically presenting with restricted knee extension, and imaging findings showing a predominantly low-signal lesion with relatively well-defined borders closely associated with the tendon sheath or joint capsule, the most likely diagnosis is Giant Cell Tumor of the Tendon Sheath (GCTTS).
If further confirmation is required, arthroscopic excision of the lesion followed by pathological examination may be considered. Additionally, other imaging sequences and certain laboratory tests could help rule out pigmented villonodular synovitis.
Treatment Strategy:
Rehabilitation/Exercise Prescription Recommendations (FITT-VP Principle):
Throughout the rehabilitation process, close attention should be paid to any pain, swelling, or other discomfort in the knee; medical consultation or adjustments to the exercise plan should be sought promptly if needed.
Disclaimer: This report is based on the available imaging and medical history, providing a preliminary analysis for reference only. It cannot replace an in-person consultation or professional medical advice. If you have any questions or your condition changes, please consult a specialist promptly.
Giant cell tumor of the tendon sheath (GCTTS)
