A 47-year-old man had suffered from prolonged fever for two months without clinical evidence of infection. Blood biochemistry and endocrine dysfunction indicated that he had pituitary insufficiency. Thorough whole body imaging studies merely identified a 22 × 14 mm mass lesion in the sella turcica. Tumor pathology and special cell marker study revealed the infiltration of atypical T-lymphoid cells and concomitant presence of some B-lymphoid cells. The fever subsided gradually following subtotal tumor resection and steroid supplementation. However, the mass lesion had invaded the cavernous sinus and optic chiasma shortly after surgery. Six months after his initial visit, metastasis lesions in the liver, the left adrenal gland, and retroperitoneal lymph nodes were discovered. In contrast to cells in the pituitary, the pathological investigation of the liver mass confirmed it to be exclusively of T-cell origin. Therefore, it is plausible that the pituitary dysfunction was related to an inflammatory process, namely hypophysitis, as well as the T-cell lymphoma. This case exemplifies the rarely noted condition of primary pituitary lymphoma with concomitant hypophysitis. Clinical diagnosis is indiscernible until the occurrence of systemic tumor metastasis.