Intravascular malignant lymphomatosis: a cause of subacute dementia.

Intravascular malignant lymphomatosis (IML) is a rare disease characterized by proliferation of neoplastic cells of lymphoid origin within small blood vessels. The median survival of IML patients is only 6 months. Any organ can be affected, with or without clinical expression. Although skin lesions are classic, they are relatively uncommon (28%). Neurological symptomatology (which evolves over a few weeks) is the most common clinical expression (83%). Dementia is the most common neurological symptom that occurs in about half of the patients with central nervous system pathology, and is associated with poorer prognosis. The diagnosis is confirmed by histology but, except for lung, biopsies are not sensitive and are helpful only when performed in the symptomatic organs; furthermore, when associated with anesthesia, they can be followed by dramatic worsening of the patient's condition. Elevated LDH is a good indicator of IML in patients with subacute neurological symptomatology, especially if associated with signs suggestive of other organ involvement.