Background: Behçet disease may be confused with sarcoidosis because they are both multisystem inflammatory disorders presenting with uveitis, polyarthritis, cardiovascular disease, erythema nodosum, and other cutaneous lesions. The coexistence of Behçet disease and sarcoidosis is extremely rare but not impossible. Vascular involvement is a significant pathological finding in Behçet disease, and arterial aneurysm formation is more common than occlusion. However, large-vessel vasculitis associated with sarcoidosis is extremely rare. Case Report: A 23-year-old man was admitted to the hospital because of swelling and pain in the right groin. The patient, who had predominant Behçet disease, was also diagnosed with sarcoidosis during the examination. He had inguinal distention associated with femoral artery aneurysm and underwent successful surgery without complication. Conclusion: Assessment of the coexistence of Behçet disease and sarcoidosis is critical because of their potentially fatal effects by triggering systemic inflammation. Furthermore, arterial diseases, especially those developing at young ages, can be a sign of immunoinflammatory disease.