[Malignant meningeal "histiocytosis"]. / Meningeale maligne "Histiozytose".

Two cases of patients with unusual pleomorphic tumors in the meninges are reported. Histologically and immunohistologically, the tumor cells may be histiocytic in appearance. Computed tomography and magnetic resonance imaging scans, however, revealed no lesions in the parenchyma or in the meninges. The cytological examination of the cerebrospinal fluid revealed only a light lymphocytic reaction without tumor cells in both cases and thus led to misinterpretations as meningoencephalitis. One patient presented psychiatric symptoms. Related clinical problems and the possible histogenesis of the tumors are discussed.

Monocytoid B-cell lymphoma: its relationship to and possible cellular origin from marginal zone cells.

Monocytoid B-cell lymphoma, the neoplastic counterpart of the monocytoid B cells, is a now well-recognized variant of low-grade, malignant B-cell lymphomas. However, monocytoid B-cell lymphomas state of differentiation, its cellular origin, and its relationship to other B-cell compartments are still obscure. We investigated an unusual case of monocytoid B-cell lymphoma with generalized disease at presentation, including infiltration of the abdominal lymph nodes, spleen, liver, and bone marrow, as well as involvement of the peripheral blood. The tumor showed the typical sinusoidal and perifollicular growth pattern in the lymph nodes. In the spleen the main infiltrate was confined to the marginal zone. These features and the characteristic immunoreactivity of the tumor cells (KiM1P+, KiB3-) in our case suggest that monocytoid B cells and their neoplastic counterparts are closely related to and probably derived from marginal zone cells.

[Intracerebral gliofibroma]. / Intrazerebrales Gliofibrom.

A 14-month-old girl had three epileptiform attacks in the course of 6 months, each consisting of rhythmic movements of the right arm and right hand of 5 minutes' duration, followed by a 15-minute period of weakness. There were otherwise no abnormal neurological signs. Prenatal and perinatal development had been uneventful and the mother was healthy. Computed tomography showed a tumour in the left frontoparietal region. Surgery revealed an intracerebral tumour 7 cm in diameter with two large cysts; it was not sharply demarcated from the brain parenchyma, had no connection with the dura and was not infiltrating the ventricular system. The tumour was completely removed and at follow-up 18 months later there was no evidence of recurrence. Histological and immunohistochemical investigations showed that the tumour consisted of closely interwoven astrocytes and fibroblasts, two different cell types the latter of which does not normally occur in the brain. Exact immunohistochemical analysis of the components of a tumour is important because, unlike pure glial tumours, gliofibromas have a good prognosis after complete resections.