The diagnosis is usually made on the clinical appearance alone, and biopsy is not usually indicated. The histologic appearance is one of marked hyperparakeratosis producing a ragged surface with many projections of keratin. Typically there is superficial colonization by bacteria. There may be vacuolated cells in the upper portion of the prickle cell layer. There is a similarity between this appearance and that of hairy leukoplakia, linea alba and leukoedema. In people with human immunodeficiency virus, who are at higher risk of oral hairy leukoplakia, a tissue biopsy may be required to differentiate between this and frictional keratosis from cheek and tongue chewing. Classification<unk>  is a type of frictional keratosis. The term is derived from the Latin words, morusus meaning "bite" and bucca meaning "cheek". This term has been described as "a classic example of medical terminology gone astray". The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) classifies the condition under "Other Specified Obsessive-Compulsive and Related Disorder" (300.3) as a body-focused repetitive behavior; the DSM-5 uses the more descriptive terms lip biting and cheek chewing (p. 263) instead of<unk> .
Morsicatio buccarum
Visceroptosis
Oral galvanism
Cimex hemipterus
Trichostasis spinulosa
Dens evaginatus
Crepitus
Status marmoratus