Lichen planus* is a chronic inflammatory disease
involving skin and oral mucosa. It represents
an immune abnormality involving T lymphocytes
sensitized to antigens in the overlying stratified
squamous epithelium. Often it is associated
with medications the patient is taking, and it is
then called a lichenoid mucositis secondary to
medications. Classic lichen planus and drugrelated
lichenoid mucositis appear identical
clinically and microscopically