A case of lymphocytic hypophysitis initially diagnosed as aseptic meningitis

A 57-year-old man presented with headache and fever, and was diagnosed as having aseptic meningitis on the basis of CSF pleocytosis. One month later, the symptoms became exacerbated, and lethargy also developed. Although general blood tests including electrolytes and creatine kinase showed no abnormalities, brain MRI with Gd-enhancement revealed enlargement of the whole pituitary gland, spreading to the stalk. Hormonal tests revealed pan-hypopituitarism. After ruling out diseases such as sarcoidosis, syphilis, tuberculosis, Sjögren syndrome and systemic lupus erythematosus, which could potentially cause hypophysitis, lymphocytic hypophysitis was diagnosed. Hormone replacement therapy ameliorated both the symptoms and the enlargement of the pituitary gland. This case was considered to be atypical lymphocytic hypophysitis, lacking abnormalities in general blood tests, which is essential when considering a differential diagnosis of aseptic meningitis.