The strange colour of Giulia’s tongue

A multi-factorial etiology

Lingua villosa nigra, or black hairy tongue, is a predominantly asymptomatic benign medical condition, characterized by hypertrophy and/or reduced desquamation of the filiform papillae on the rear of the tongue, which is coloured dark brown to black. Lingua villosa can also be white, green, blue or yellow in appearance.^1,2,3 The specific colour seems to be due to the accumulation of pigmented bacteria or fungi within the excessively elongated filiform papillae.^2-4 The diagnosis is essentially clinical, and the symptoms which are sometimes associated are: alterations in taste, metallic taste in the mouth, halitosis, a choking or tingling sensation, nausea and xerostomia.^1,2,5 The etiology remains unclear, and is often multifactorial, i.e. resulting from a combination of local and systemic problems. There are numerous predisposing factors, such as smoking, taking topical or systemic antibiotics, or bismuth, or systemic corticosteroid therapy, poor oral hygiene, yeast infections and radiation therapy.¹ The mechanism by which drugs cause this condition is unclear. Prevalence increases with age and varies in general, being three times more common in men than women, due to the presence of major risk factors.¹ In the literature there are several case reports about the occurrence of lingua villosa nera in adults as well as in children, in which, however, this reaction is not frequent.^6-7 In Julia's case, it is possible that the reaction was incurred after antibiotic therapy, although it was not shown in the SPC for the specialty prescribed to the child. The Micromedex Database reports that this reaction has been recorded in some SPRs for drugs marketed in Italy.⁸ Of note, however, is the fact that the onset of lingua villosa nera is known, both in Italy and in other countries, for the combination amoxicillin plus clavulanic acid. In the Italian Database for reporting adverse reactions, there are three other reports of lingua nera caused by therapy with amoxicillin, whilst the Dutch Database, up to 2009, had received 37 reports of this drug combination/reaction.⁹ However, predisposing factors in clinical histories have not been excluded.
Currently, there are no guidelines for the treatment of lingua villosa nera, and the response to prescribed curative therapy depends very much on the underlying conditions and respect of same. In adults, the pathological condition may persist for years, whilst in children, it usually resolves within a few weeks. The first action to implement is the suspension of potentially offending agents, and modification of any predisposing factors (such as smoking and poor oral hygiene). Benefits can also be achieved by hydration and salivation (perhaps through the use of chewing gum), the use of a soft toothbrush to scrape the tongue to promote desquamation of keratinised papillae, topical application of sodium bicarbonate or rinsing the mouth with a dilute solution of hydrogen peroxide. Rarely, surgical excision is needed to resolve the condition.^1,2,6 In Julia's case, there was a complete regression of the condition in one month, due to suspension of the suspected drug, combined with good oral hygiene.