A case of high-grade non-Hodgkin's malignant lymphoma with an immunologically proven B-cell origin is reported; 20 to 30 per cent of the neoplastic cells displayed electron-dense neurosecretory-like granules at the ultrastructural level. This observation confirms the existence of such a finding in lymphomatous growths and stresses its irrelevance in the differential diagnosis between non-Hodgkin's malignant lymphomas and apudomas.