[Meningeal infiltration of malignant lymphoma presenting with Froin's syndrome].

Froin's syndrome is characterized by a combination of marked coagulation, elevated protein levels, and xanthochromia of the cerebrospinal fluid (CSF). It is due to blockage of CSF flow by a spinal cord mass or results from meningeal irritation during meningitis. However, Froin's syndrome has not been reported in hematological malignancies. Herein, we present two cases of lymphomatous leptomeningitis with Froin's syndrome. A 66-year-old man suffered consciousness disturbance during chemotherapy for a relapse of peripheral T-cell lymphoma, not otherwise specified. An 84-year-old man complained of pain and paralysis in both legs during chemotherapy for diffuse large B-cell lymphoma. In both cases, CSF analysis showed indications of Froin's syndrome, and cytology revealed lymphoma cells. In contrast to the highly elevated CSF protein levels, normal to only mildly elevated cell counts were not associated with advanced leptomeningeal disease. This is the first case report of leptomeningeal involvement in hematological malignancy associated with Froin's syndrome. As there are potentially undiagnosed cases including mild forms, Froin's syndrome should be kept in mind during CSF examination of patients with hematological malignancies.