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.