desquamative gingivitis (DG) – A clinical term used to describe gingival tissues that demonstrate potentially painful erythema, hemorrhage, sloughing, erosion, and ulceration.

direct immunofluorescence – Fluorescence microscopy technique designed to identify specific autoantibodies in the biopsied tissue.

exfoliative cytology – The microscopic examination of cells that have been shed from a lesion or have been recovered from a tissue for the diagnosis of disease. Also called cytopathology.

indirect immunofluorescence – Fluorescence microscopy designed to detect the presence of autoantibodies in the patient's serum.

Nikolsky’s sign – Epithelial desquamation that is induced by the application of a firm sliding or rubbing force. This phenomenon is commonly observed in several mucocutaneous disease states.

patch test – A type of skin test for hypersensitivity in which filter paper or gauze saturated with the substance in question is applied to the skin, often on the back; a positive reaction is characterized by reddening or swelling at the site.

reflective confocal microscopy – An in vivo, non-invasive, autofluorescence microscope that is able to penetrate body tissues and to show the cytoplasm of epithelial cells, connective tissue cells, blood vessels, etc. Studies are underway to identify specific confocal features of lesions that are consistent with those found in conventional histologic microscopy, thereby enabling the diagnosis of a lesion without requiring a biopsy.

vesiculobullous disease – A type of mucocutaneous disease that is characterized by vesicles and bullae (i.e., blisters). Both vesicles and bullae are fluid-filled lesions, and they are distinguished by size (vesicles being less than 5-10 mm and bulla being larger than 5-10 mm).