Abstract
RATIONALE: Lipoma arborescens (LA) is a rare, benign proliferative disorder of the synovial lining that typically affects middle-aged individuals, predominantly in the knee joint. However, its occurrence in younger patients is unusual and may pose unique diagnostic and therapeutic challenges. This case report aims to highlight the clinical, imaging, and therapeutic aspects of LA in a young adult, thereby expanding the understanding of its presentation in this age group. PATIENT CONCERNS: A 22-year-old male presented with acute swelling and pain in the right knee following a minor sprain. Although the symptoms persisted and worsened over several days, the patient was particularly concerned about his prognosis and the possibility of recurrence. Given the rarity of LA, he expressed anxiety about being diagnosed with such an uncommon condition at his age and feared the potential impact on his future mobility. He was also apprehensive about the risks of surgery and questioned why he, at such a young age, was affected by this rare condition. DIAGNOSES: Initial clinical assessment was inconclusive, leading to further investigations. Magnetic resonance imaging findings suggested a meniscal tear and the presence of LA, characterized by fat globules and joint effusion, which was confirmed during arthroscopic surgery. INTERVENTIONS: The patient underwent arthroscopic surgery involving trimming of the medial meniscus and debridement of the synovium. Surgical findings included extensive synovial proliferation and intra-articular fat globules, which were histologically confirmed as LA. OUTCOMES: Postoperative recovery was successful, with significant improvement in joint function and alleviation of symptoms. Follow-up magnetic resonance imaging confirmed the absence of abnormal synovial proliferation. LESSONS: This case report underscores the diagnostic and therapeutic challenges associated with LA in a young patient, highlighting the importance of considering LA in differential diagnoses of acute knee swelling, especially when initial evaluations are inconclusive. Through a combination of imaging, arthroscopic intervention, and histopathological confirmation, this case illustrates an effective approach for accurately diagnosing and managing LA. By documenting this atypical presentation in a young adult, this report contributes to the limited literature on LA in younger populations, aiming to enhance clinical awareness and guide future cases involving similar joint lesions.