52 year old male with no past medical history presents to the emergency department with 3 months of increasing fatigue, upper extremity weakness, and oropharyngeal dysphagia. Review of systems was notable for fevers, chills and a 10kg weight loss over the same time period. Physical exam revealed a papular rash with scaling raised lesions over his hands and fingers bilaterally and proximal upper extremity weakness. Initial basic labs were unremarkable other than mild elevations in the erythrocyte sedimentation rate and creatinine kinase. A chest X-ray lesion prompted a CT of the chest which revealed a spiculated, noncalcified right apical nodule and extensive lymphadenopathy. Bronchoscopy with biopsy revealed non-small cell lung cancer and he was diagnosed clinically with cancer-associated myositis based upon exam findings of muscle weakness, dysphagia, and Gottron papules. Additional labs including serum aldolase and myositis-specific antibodies later returned negative. He was treated with chemotherapy and radiation, in addition to steroids. His proximal muscle weakness and dysphagia progressed rapidly despite increasing doses of steroids. The cancer also progressed despite treatement, and he died within 3 months of diagnosis.
Cancer-associated myositis (CAM) usually presents with features similar to dermatomyositis (DM). It is thought that CAM is driven by antibodies directed against tumor cells that cross react with muscle and skin cells resulting in a paraneoplastic-type syndrome. Features most-associated with the presence of malignancy at diagnosis include: age greater than 52, shorter time between onset of symptoms and diagnosis, and the presence of Gottron papules. DM seems to carry a higher risk of associated malignancies than polymyositis (PM). Patients carry an elevated risk of malignancy within the 2 years before and after a diagnosis of DM or PM, with many cancers being diagnosed simultaneously. Interestingly, CAM is often not associated with more typical myositis-specific autoantibodies which supports the finding that malignancy is only present in a subset of myositis patients. While prognosis is determined by the underlying cancer, prognosis appears to be worse when CAM is present. Moreover, control of CAM symptoms is only reported in those with cancer remission. Current recommendations suggest age-appropriate cancer screening in all patients diagnosed with myositis, keeping in mind that certain features may predict a higher likelihood of simultaneous neoplasm.
CAM is a rare but important diagnosis often made in the inpatient setting. Hospitalists should consider a more intensive search for malignancy in older patients presenting with rapid onset of myositis symptoms and characteristic skin findings.