We report here an unusual case of extensive ulcerative and erosive lichenoid dermatosis in a 39-year-old man with non-Hodgkin centroblastic-centrocytic B-cell lymphoma. The simultaneous presentation of the lichenoid eruption and malignant lymphoma favored a causal relationship between the two conditions. It is suggested that the lichenoid cellular reaction may be an immunological response to some yet-unidentified tumor products. Electron-microscopic examination revealed apoptotic keratinocytes with filamentous degeneration in the epidermis. In the upper dermis many globular filamentous bodies (Civatte bodies) composed of densely packed wavy filaments 6–12 nm in diameter and a varying number of cytoplasmic organelles were identified. Serial skin biopsies showed the evolution of the lichenoid lesion with time and treatment. Large numbers of colloid bodies were seen in persistent lesions but were absent in healed ones. The characteristic wavy nature of the filaments was maintained and no transition to the straight fibrils of amyloid was observed. The relationship between colloid bodies and amyloid is discussed.