A 30-year-old healthy woman presented with 2 days of severe headaches, fever, dizziness and then worsening vision rapidly developed. She was found to have polydipsia and polyuria with signs of dehydration. The clinical features of this patient were suggestive of pituitary apoplexy. CT-scan and brain MR-imaging showed a 36-mm hypothalamic mass with suprasellar extension and optic chiasm infiltration (Pictures 1, 2). Hormonal profiles revealed low levels of cortisol and thyroxine with a hyperprolactinemia. Hormonal substitution was administered. A CT-scan stereotactic biopsy was performed. Pathologic examination revealed a malignant large B cell lymphoma (CD20+). Staging work-up showed no evidence of tumor elsewhere in the body. HIV-test was negative. The patient was transferred to the department of hematology for further evaluation and chemotherapy. Unfortunately, she refused any adjuvant treatment and returned to her home. She died two months later. Few cases of primary hypothalamic lymphoma have been previously reported; the present case was the first one presenting with symptoms of pituitary apoplexy (1, 2). Hypothalamic lymphoma is not a simple clinical curiosity but a potentially life-threatening pathology regarding their metabolic complications.