Background: Lipoma arborescens (LA) is a rare, benign synovial disorder characterized by diffuse villous proliferation and replacement of the subsynovial connective tissue with mature adipocytes. Its diagnosis is often elusive due to its chronic and nonspecific clinical presentation.

Case Report: Our case involves a 27-year-old previously healthy male presenting with recurrent left knee effusions, managed conservatively with NSAIDs, corticosteroid injections, and serial arthrocentesis. Synovial fluid analysis demonstrated an inflammatory profile, and later imaging confirmed LA. Despite arthroscopic synovectomy, recurrent effusions persisted, and a polyarticular presentation involving the left elbow emerged, raising suspicion of an underlying spondyloarthropathy. Due to military service constraints, disease-modifying antirheumatic drugs (DMARDs) were initially deferred. However, following retirement, the patient started on sulfasalazine, later transitioning to adalimumab, with significant symptomatic improvement. As of January 2026, he remains asymptomatic, though a definitive diagnosis of inflammatory arthritis is pending further evaluation.

Conclusions: This case highlights lipoma arborescens as a potential manifestation of underlying inflammatory arthritis rather than an isolated synovial process, particularly in patients with recurrent or polyarticular effusions.