Median rhomboid glossitis is an enigmatic inflammatory or infectious condition of the dorsum of the tongue. Although it is benign, it can be mistaken for a serious condition by the patient or an inexperienced observer.
Median rhomboid glossitis is an uncommon condition; the estimated prevalence in adults is less than 1%, The condition is usually asymptomatic or may cause a slight burning sensation associated with spicy foods.
The etiology of this lesion is unknown. Although in the past MRG was considered a developmental failure of the branchial arches to cover the tuberculum impar, over the past 20 years, evidence of an association with candidiasis has provided a more likely pathogenesis. In the majority of cases, Candida organisms can be cultered from the lesion, and histologic examination reveals hyphae penetrating the superficial epithelium of the tongue, with focal neutrophilic microabscesses.
The most common presentation of MRG is a red or red-white patch on the midline of the dorsum of the tongue, just anterior to the region of the V of the circumvallate papillae (sulcus terminalis). The patch of reddened mucosa may be flat or raised; it is usually sharply circumscribed, with a somewhat rhomboidal shape. Occasionally, there is a nodular component, or the lesion may be lobulated. The texture may be similar to the surrounding tongue or firm, and the surface is relatively smooth.