The nevus, colloquially known as mole or birthmark, is an either congenital or acquired malformation of the skin, representing a benign neoplasm of cutaneous melanocytes.
Melanocytic nevi are sharply defined, vary greatly in shape (but are symmetric), are uniformly coloured and appear commonly as slightly raised papule. The intramucosal nevus represents the most frequent subtype of the nevi. It is brown in colour and most often found in the buccal mucosa. The similarly common blue nevi are most frequently located on the hard palate.
The majority of nevi develop on the skin, making the oral mucosa a rather rarely affected area. The average age of affected humans is 38 years. Rare cases of nevi turning into malignancy are reported.