Plasmacytosis, a benign inflammatory disease rarely found in the oral cavity, is microscopically characterized with intensive subepithelial plasmacyte infiltrate. We have recently experienced a case of plasmacytosis in the lower lip of a 68-year-old woman and reported on it with some comments. As clinical findings, the lower lip was slightly reddish with crossed white lines forming a lace pattern. Histopathological examination showed severe submucosal infiltrate of polyclonal (posotive for both λ and κ chain) plasmacytes and it was diagnosed as plasmacytosis. A steroid ointment was topically applied to the lower lip. About 4 weeks after the treatment the lesions comlpetely disappeared. The prognosis is fairly good and there is no recurrence after one year and ten months.
