REN and systemic sclerosis: Scleroderma renal crisis (SRC) is the most common hallmark of renal involvement in systemic sclerosis (SSc), characterized by acute kidney injury and malignant hypertension. The pathophysiology of SRC involves endothelial dysfunction, activation of the renin-angiotensin-aldosterone system (RAAS), and thrombotic microangiopathy (TMA), leading to renal ischemia and hypertension.