It is seen in patients using inhaled steroids and smokers, and is usually a kind of chronic atrophic oral candidiasis, but hematinic deficiency and diabetes should be excluded.

The typical appearance of the lesion is an oval or rhomboid shaped area located in the midline of the dorsal surface of the tongue, just anterior (in front) of the sulcus terminalis.

There may be candidal lesions at other sites in the mouth, which may lead to a diagnosis of chronic multifocal oral candidiasis.

Predisposing factors include smoking, denture wearing, use of corticosteroid sprays or inhalers and human immunodeficiency virus (HIV) infection.

This was disproved when a study of 10,000 children were examined and no medium rhomboid glossitis lesions were found at all.