Contracturing Granulomatous Myositis with Recurrent Malignant Thymoma and Myasthenia Gravis: A Case Report

Contracturing granulomatous myositis (CGM) is a very rare myopathic syndrome where patients present with slowly progressive muscle pain or weakness affecting mainly proximal muscles together with flexion contractures of the limbs. To date, there have only been several case reports of CGM, which have been reported to occur most commonly in association with sarcoidosis. We report a case of CGM associated with recurrent malignant thymoma and myasthenia gravis (MG). A gentleman with history of treated malignant thymoma presented with new onset proximal muscle weakness and pain that later evolved into contractures that persisted despite treatment with steroids and intravenous immunoglobulin. A malignancy workup revealed recurrence of his malignant thymoma warranting chemotherapy treatment. His contractures only resolved after addition of chemotherapy treatment. He later developed clinical features of MG 1 year after his initial elevation in Anti-acetylcholine (Anti-AChR) antibody levels. We postulate CGM to be a paraneoplastic phenomenon of underlying malignant thymoma. Treatment of thymoma together with immunosuppressive therapies led to clinical improvement of our patient’s CGM. The sole elevation of Anti-AChR levels without the accompanying clinical features does not equate to a MG diagnosis, but should raise the clinician’s vigilance for future development of the condition.