Polymyositis with respiratory muscle weakness requiring mechanical ventilation in a patient with metastatic thymoma treated with octreotide

Although most patients with thymoma present with a mediastinal mass amenabl e to surgical resection, some patients develop metastatic disease requiring systemic therapy. The majority of thymomas express somatostatin receptors as demonstrated by octreotide scanning, an observation which has prompted t he clinical use of octreotide in patients with this disease. Many patients with thymoma exhibit autoimmune paraneoplastic syndromes, most frequently m yesthenia gravis. We report here the case of a patient with metastatic thym oma who developed a profound autoimmune polymyositis and lupus-like syndrom e that flared following treatment with octreotide and was associated with a clinical response to this agent. No evidence for myesthenia gravis was dis covered. The severity of the myopathy necessitated mechanical ventilation f or 12 weeks. The natural history of thymoma, treatment options including re cent combination chemotherapy regimens, and potential mechanisms for flarin g of autoimmune paraneoplastic syndromes triggered by therapy of thymoma ar e discussed.