Not a Statin-Induced Myopathy: Metastatic Pancreatic Adenocarcinoma Presenting As Paraneoplastic Myositis

Abstract

LEARNING OBJECTIVE #1: Recognize the clinical features of polymyositis as a paraneoplastic syndrome LEARNING OBJECTIVE #2: Treat inflammatory polymyositis secondary to underlying malignancy CASE: An 81-year-old male with a history of hyperlipidemia on a statin and no recent trauma, who presented with generalized myalgias, was found to have rhabdomyolysis. Stable vitals on admission and labs showed CK of 6059 U/l, ESR of 108 mm/h, and elevated CRP of 15.3. Statin was stopped, and the patient was treated with IV crystalloids and steroids. The hospital course was complicated by sepsis secondary to cholangitis, for which the patient received ceftriaxone and metronidazole. CT scan of the abdomen was unremarkable. MRCP showed evidence of 15 mm dilated distal common bile duct,10 mm dilated pancreatic duct, and ampulla with a nonspecific 0.6 cm soft tissue density. CA 19-9 was elevated to 9298 U/ml. The patient underwent ERCP with sphincterotomy and biopsy, which revealed the diagnosis of metastatic pancreatic adenocarcinoma. After ductal decompression with sphincterotomy and antibiotic therapy, the patient clinically improved. Additionally, the patient underwent an MRI of the right thigh, and findings were consistent with severe inflammatory myopathy with significant diffuse subcutaneous myofascial edema without focal abscess or necrosis. Muscle biopsy showed scattered nuclear clumps and rare myofiber necrosis without inflammation. Myositis/ antiJo1 extensive antibody panel was negative. Finally, polymyositis was found to be a paraneoplastic presentation of myopathy/myositis secondary to pancreatic adenocarcinoma, and the diagnosis was confirmed with a muscle biopsy and highly compatible imaging findings. The patient was treated with systemic steroids reaching clinical and laboratory improvement. Ultimately, the patient underwent pancreaticoduodenectomy. IMPACT/DISCUSSION: Polymyositis in the elderly population can present as a paraneoplastic syndrome and is strongly associated with underlying cancer. A muscle biopsy is necessary to establish the diagnosis, as only 30% of patients have positive antibody panels. Lung cancer, rectum and colon cancer, pancreatic cancer, kidney cancer, stomach cancer, breast cancer are the most associated with inflammatory myositis in the descending order. The cornerstone treatment of paraneoplastic myositis/myelopathy stays immunosuppression with glucocorticoids in conjunction with specific cancer treatment. CONCLUSION: Polymyositis is a paraneoplastic syndrome that can be associated with pancreatic cancer. Clinicians should be aware of this syndrome as the ability to diagnose and treat paraneoplastic syndromes may impact health outcomes, from early detection of cancer to improving quality of life.