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Giant cell myositis associated with metastatic thymoma and granulomatous hypercalcaemia
  1. Jessica C Jimenez1,
  2. Calixto-Hope G Lucas2,
  3. Sara C LaHue1,3 and
  4. Bradley A Sharpe4
  1. 1Department of Neurology, University of California San Francisco School of Medicine, San Francisco, California, USA
  2. 2Department of Pathology, University of California San Francisco, San Francisco, California, USA
  3. 3Department of Neurology, University of California San Francisco Weill Institute for Neurosciences, San Francisco, California, USA
  4. 4Department of Medicine, University of California San Francisco, San Francisco, California, USA
  1. Correspondence to Dr Bradley A Sharpe; bradley.sharpe{at}


Giant cell myositis (GCM) is a rare inflammatory myopathy associated with myasthenia gravis and thymoma. Here, we report on a woman in her late 50s with a history of myasthenia gravis, systemic lupus erythematosus and stage IV thymoma with pleural metastases, who presented with proximal weakness, neuromuscular respiratory failure and hypercalcaemia. She was diagnosed with GCM via muscle biopsy and screened for myocarditis but showed no evidence of myocardial involvement. Her hypercalcaemia was consistent with a granulomatous process, likely driven by her GCM. Her strength gradually improved, and her hypercalcaemia did not recur after treatment with high dose steroids, intravenous immune globulin and plasma exchange. Her course was complicated by several opportunistic infections in the setting of her immunosuppression. Despite the high morbidity associated with GCM, she demonstrated clinical improvement after initiating immunosuppressive therapy and continues to be managed in the outpatient setting.

  • Muscle disease
  • Pathology
  • Musculoskeletal syndromes
  • Calcium and bone
  • Neuromuscular disease

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  • Contributors JCJ and BAS conceived the idea. JCJ and SCLH determined the discussion points. JCJ and C-HGL prepared the figures. Monica Yang provided feedback on the manuscript. All authors contributed to manuscript preparation and were directly involved in the patient’s care.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.