Myasthenia gravis (MG) is in 15% of cases a paraneoplastic phenomenon secondary to a thymoma. A subset of these will have both a thymoma and associated immunodeficiency known as Good’s syndrome. Immunological features include hypogammaglobulinaemia, a reduction in peripheral B cells, CD4+ lymphopenia, and reversal of CD4/CD8 ratio.

We present two cases followed by a literature review:

1. 52 year–old man presented with dysphagia, diagnosed as MG. He was found to have a stage 4a thymoma (histology B2), subsequently resected. He was noted to have a reduction in peripheral B cells and CD4+ lymphopenia suggestive of Good’s syndrome. He has also had chronic diarrhoea and recurrent pulmonary infections with Pseudomonas, Klebsiella and Mycobacterium abscessus. Current immunotherapy includes prednisolone.

2. 42 year–old woman presented with a myasthenic crisis requiring ITU admission. She was found to have a thymoma (histology B3), treated with resection and adjuvant radiotherapy. Peripheral B cell reduction led to a diagnosis of Good’s syndrome. She is currently in remission on prednisolone, mycophenolate mofetil and 6–weekly immunoglobulin infusions.

These cases illustrate that Good’s syndrome is an important differential when managing patients with myasthenia gravis, especially as the immunodeficiency may precede or occur after the diagnosis of a thymoma.