Cytoplasmic tubular structures in the diagnosis of oral discoid lupus erythematosus.

Biopsies from oral lesions of 5 patients with discoid lupus erythematosus (DLE), 5 with lichen planus (LP), 5 with leukoplakia (LEUK) and 3 patients with uncertain diagnoses termed DLE?, LP? were examined in the electron microscope for presence of cytoplasmic tubular structures (CTS) in vascular endothelium. Five vessels were examined in each of two randomly selected sections from each biopsy, without knowledge of the clinical diagnosis. All five DLE biopsies showed presence of CTS in 4-9 out of 10 vessels, as compared with none of 10 vessels in biopsies from LP or LEUK, the difference being significant. Further, CTS occurred in 4 out of 10 vessels in one DLE?, LP? biopsy from a patient with serologic signs of systemic lupus erythematosus. As CTS seem to be absent in oral lesions of LP and LEUK, which are the most important differential diagnoses for oral DLE, the identification of CTS in vascular endothelium sing electron microscopy may be an auxiliary diagnostic procedure in oral DLE.