Chronic lymphocytic leukemia with hypothalamic invasion

Headaches and a state of confusion developed in a patient with chronic lymphocytic leukemia (CLL). A computed tomography (CT) scan of the head showed a hyperdense lesion in the hypothalamus with obstruction of the foramina of Monro. Leukemic cells with monoclonal lambda B‐cell markers were identified in the ventricular fluid at the time of surgical decompression. Similar cells were identified in the peripheral blood. This lesion has not been described as a complication of CLL, a disease that, unlike other leukemias, rarely has central nervous system manifestations.