When Chest Pain Defies Coronary Assumptions, Remember Scleroderma

Introduction: Systemic sclerosis (SSc) is an autoimmune connective tissue disorder affecting multiple organ systems. Scleroderma renal crisis (SRC) is a potentially life-threatening manifestation that requires early recognition. Case Description: A 66-year-old man with hypertension presented with uncontrolled hypertension and chest pain. He was found to have an NSTEMI and newly decompensated heart failure with an ejection fraction of 25%, but coronary angiography revealed nonobstructive disease. Concurrently, he had an acute kidney injury (creatinine 1.5 mg/dL, baseline 0.9 mg/dL) presumed secondary to cardiorenal syndrome. However, serial UPCRs were 0.19-0.65 g/g, urinalyses showed intermittent hematuria, and post-discharge kidney function worsened (peak creatinine 3.4 mg/dL). Importantly, exam was remarkable for joint stiffness and skin tightness, prompting a kidney biopsy that demonstrated thrombotic microangiopathic angiopathy. Rheumatologic evaluation yielded elevated anti-RNA polymerase III antibodies and negative anti-SCl70. He was started on mycophenolate and captopril for SRC, and creatinine stabilized at 2.6 mg/dL. Discussion: Systemic sclerosis is a rare diagnosis. Our patient presented with many atypical features, including age of onset, gender, absence of preceding Raynaud phenomenon, and initial presentation with a primary cardiac concern. SRC is also rare, affecting 5-10% of patients with SSc. It is marked by acute severe range hypertension, acute kidney injury, and mild proteinuria. As seen in this case, renal biopsy shows thrombotic microangiopathy due to pathologic disruption of the endothelin pathway. This case highlights the importance of considering uncommon diseases even in patients presenting with common concerns, and revisiting the differential diagnosis when available data do not support a working diagnosis (in this case, coronary angiography revealing nonobstructive disease). Clinicians should maintain a high level of suspicion for this rare disease in patients with skin and musculoskeletal changes. Anti-RNA polymerase III antibodies should be checked as soon as possible in patients with suspected renal involvement.