63-year-old man who reports a long-standing, painless, slowly progressive swelling of the joint with recurrent effusions.
An MRI was made in order to make an accurate diagnosis for an intraarticular pathology. MRI was enough for making the diagnosis of a noninfectious synovial proliferative process (i.e lipoma arborescen). T1-weighted and fat-suppressed sequences were used in this study.
Lipoma arborescens is a rare intraarticular lesion characterized by the replacement of the subsynovial tissue by mature fat cells, giving rise to a villous synovial proliferation. Lipoma arborescens is usually monarticular and occurs most frequently in the knee, particularly in the suprapatellar pouch. Most patients are in the 5th to 7th decades of life. Affected patients usually report a long-standing, painless, slowly progressive swelling of the joint with recurrent effusions. The exact cause is unknown, but the most accepted hypothesis suggests that lipoma arborescens represents a nonspecific synovial reaction to inflammatory or traumatic stimuli rather than a neoplasm. Synovectomy is the definitive treatment. Postoperative recurrence is uncommon. Lipoma arborescens has many characteristic imaging findings that allow for a confident diagnosis. Radiographs typically show joint fullness and, frequently, osteoarthritic changes. These findings are nonspecific, and the diagnosis can be suspected only when radiolucent areas suggestive of fat are seen in a joint space. US demonstrates a hyperechoic, frondlike mass that bends and waves in real time during joint manipulation. The characteristic subsynovial hypertrophic adipose proliferation allows for a precise diagnosis with MR imaging, especially when T1-weighted and fat-suppressed sequences are used, since the lesion has fat signal intensity with all mpulse sequences. Differential diagnosis, Noninfectious Synovial Proliferative Processes: Synovial Osteochondromatosis. Pigmented Villonodular Synovitis Rheumatoid Arthritis.
Lipoma Arboresccens.
Based on the provided MRI images of the knee joint, there is a flocculent or villous proliferative tissue signal within the joint capsule. This tissue appears as high signal intensity on T1-weighted images and becomes relatively low or suppressed on fat suppression sequences (for instance, T2 fat suppression or STIR), indicating that its main component is adipose tissue. The lesion commonly involves the synovium and the suprapatellar recesses of the knee joint (particularly the suprapatellar pouch), where villous thickening of the synovium can be observed. The joint alignment is normal, and there is no obvious evidence of fracture. Some patients may also exhibit certain degrees of osteoarthritic changes (such as subchondral bone thinning, articular surface wear, mild joint effusion, etc.) as well as fluid in surrounding soft-tissue spaces.
Considering the patient’s age (63 years), clinical presentation (long-term, painless, gradually progressive joint swelling with recurrent effusion), and the characteristic adipose signal on MRI, the most likely diagnosis is Lipoma arborescens. If there is any doubt, arthroscopic synovial biopsy or further examinations may be performed to confirm the diagnosis. However, the imaging findings are highly specific and are usually sufficient for definitive diagnosis.
Treatment Strategies:
Rehabilitation and Exercise Prescription (FITT-VP Principle Example):
Throughout this process, it is particularly important to monitor joint swelling, pain, and inflammation. If significant discomfort arises, the rehabilitation plan should be adjusted promptly, and a follow-up evaluation may be necessary.
This report is based solely on the available imaging and clinical information and serves as a reference. It does not replace in-person consultation or the diagnosis and treatment plan provided by a professional physician. If you have any doubts or if your condition changes, please visit a hospital for prompt evaluation and follow the specialist’s guidance.
Lipoma Arboresccens.
