What’s causing this lump on the top of the shoulder? 🤔 That visible lump is often an AC joint cyst, most commonly caused by a chronic full-thickness rotator cuff tear — a classic finding known as the ✨ Geyser Sign ✨ 👇 Here’s what’s happening 👇 🔹 A long-standing rotator cuff tear disrupts the normal barrier that keeps joint fluid contained 🔹 Joint fluid escapes upward from the shoulder 🔹 The humeral head migrates superiorly and the AC joint capsule weakens 🔹 Fluid travels through the subac