SERONEGATIVE IMMUNE-MEDIATED NECROTIZING MYOPATHY Raja Prahadeesh, Saravanan, Apoorva Malipeddy, Karthik Reddy; Department of Medicine, Baton Rouge General Medical Center, Baton Rouge, LA.
Introduction: Immune-mediated necrotizing myopathy is an uncommon subtype in the myositis spectrum characterized by proximal muscle weakness and rhabdomyolysis secondary to myonecrosis. IMNM is further classified into three subtypes based on autoantibody serology: Anti-HMGCR, anti-SRP and seronegative. Amongst these, seronegative IMMN is the least reported and often misdiagnosed as polymyositis or statin-induced myositis. Case: A 79-year-old male presented with a two- week history of progressively worsening walking difficulty, poor appetite, and weight loss. His medical history includes previously treated prostate and laryngeal cancers, hypertension, and dyslipidemia. Physical examination was significant for decreased strength in the proximal muscles of the bilateral lower (2/5) and upper extremities (4/5) and icterus. Initial labs revealed elevated creatinine kinase (22,806), BUN (64), creatinine (3.43), potassium (5.8), ALT (1100), AST (1694), and total bilirubin (4.6). The patient was initially believed to have statin- induced rhabdomyolysis, and treatment was initiated with fluid and bicarbonate infusion. Atorvastatin was discontinued. However, there was no improvement in his clinical condition. By day 5, his creatinine kinase trended to 157,580 with worsening renal
function and anuria. At this point, hemodialysis was initiated. A muscle biopsy and further work-up were done. MRI of the thighs showed evidence of diffuse myositis and fasciitis. He was commenced on methyl prednisone. Renal biopsy showed acute tubular necrosis in the presence of myoglobin casts on underlying diabetic glomerulopathy. Muscle biopsy showed necrotizing myopathy with enhanced MHC and MAC staining on the sarcolemma membranes without any inflammatory cells or vacuolization. Given these results, a five-day IVIG course was initiated, resulting in a dramatic drop in CK levels (4359) with significant improvement in the patient’s strength. Labs later revealed negative anti-HMGCR and anti-SRP antibodies with negative paraneoplastic and myomarker panels. A diagnosis of antibody- negative necrotizing myopathy was made. He was discharged home on a prolonged prednisone taper, with thrice weekly outpatient hemodialysis sessions. Discussion: Extremely high CK levels have been described in necrotizing myopathy, rapidly damaging the renal tubules despite hydration. Early suspicion and recognition, with the initiation of immunosuppressive therapy, is critical in preventing complications. The distinction is essential, as each subtype differs in prognosis and therapy response.
RECURRENT AORTIC DISSECTION IN YOUNG PATIENT WITH SYSTEMIC LUPUS ERYTHEMATOSUS Chelsi M. Robertson, Taylor Jindia, Kyle Stroda, Jonathan Vignes; Department of Medicine, LSU Health Sciences Center, Lafayette, LA.
Introduction: Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder, characterized by autoantibodies directed against nuclear and cytoplasmic antigens, affecting multiple organ systems. Complications of the cardiovascular system have been shown to impact the long-term prognosis. Aortic dissection is one very rare cardiovascular complication. The pathogenesis of aortic dissection in SLE patients is multifactorial, including premature atherosclerosis, vasculitis, cystic medial degeneration, as well as the effects of chronic corticosteroid therapy.
episode. He had a past medical history of SLE complicated by lupus nephritis and an ascending aortic dissection one year earlier, as well as hypertension and tobacco use. He endorsed noncompliance with his extensive medication regimen. CT angiography demonstrated a Stanford type B aortic dissection, and he was admitted to the intensive care unit for stabilization. Medical management was attempted but his symptoms continued to progress. He subsequently underwent a thoracic endovascular aortic repair with left carotid
to subclavian artery bypass. After a prolonged ICU stay including abdominal compartment syndrome requiring exploratory laparotomy, dialysis 25
Case: A 33-year-old male presented with tearing chest pain, severe hypertension, and a syncopal
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