Burkitt-type lymphoma and reticulum-cell sarcoma. An unusual mixed form of two intracranial primary malignant lymphomas.

An unusual mixed type of two primary malignant lymphomas in a 50-year-old woman is reported. The patient had been in good health until 4 months before her death, when she developed epileptic seizures and neurological symptoms attributed to a lesion of the brainstem. Pathologic examination revealed a circumscribed tumor mass in the right parietal lobe, which was shown microscopically to contain two different forms of malignant lymphoma. The histologic features of the peripheral part of the tumor were typical of a Burkitt-type lymphoma, while the central part showed the features of a reticulum-cell sarcoma. The cells of the latter type diffusely infiltrated both temporal lobes, the cerebellum, and the brainstem. It is concluded that in the absence of systemic involvement, the Burkitt-type lymphoma also could be derived from the primitive reticulum cells of perivascular sheaths.