NL Journal of Dentistry and Oral Sciences
(ISSN: 3049-1053)

Case Presentation

A 47 year male patient is presented with a loss of appetite, metallic taste and chronic granulomatous ulceration on the lateral border of the tongue along with black coating on the dorsal surface of the tongue consistent with BHT, which was asymptomatic since 5 days. He gave the history of taking the prescribed Metronidazole 400 (Per Oral thrice daily ) and Doxycycline mouthwash (100 mg : 15 mL) for last 7 days. There were no signs of lymphadenopathy, rash or joint swelling. Full blood count, Hb%, renal function, liver function and viral screening were within normal range. Consequently, we concluded that the most probable diagnosis was BHT secondary to metronidazole or topical broad spectrum antibiotic Doxycycline. The oral condition was examined properly and sharp edges of teeth were found at the offending side which had been causing frictional trauma on the lateral border of the tongue. The sharp edges of teeth were removed by selective grinding and he was prescribed with anesthetic topical gel for symptomatic relief and topical application of amlexanox (5%), chlorhexidine ointment for ulceration and topical antifungal (clotrimazole) and topical corticosteroid (Triamcinolone acetonide) along with Vit A and retinoids for BHT. Patient reported after 5 days with complete remission of BHT and much better healed traumatic tongue ulcer.

Fig 1 - Antibiotic induced BHT with ulceration on the lateral border of the tongue
Fig 2 - Remission of BHT along with ulceration

Discussion

It is thought that bacterial or fungal infection causes the discoloration of the dorsal surface of the tongue. Differential diagnosis include acanthosis nigricans, oral hairy leukoplakia, pigmented filiform papillae, Addison’s disease or black staining due to food colouring. Acanthosis nigricans in the oral cavity manifests as multiple dark and demarcated papillary lesions on the dorsum and lateral region of the tongue with frequent labial involvement and may be associated with underlying malignancy [3,4]. Different reports suggested that Bacillus subtilis or Candida sp infections may cause BHT. Based on animal experiments, it has been suggested that Bacillus subtilis varietas niger infection causes BHT [5,6].

Prevention and treatment of BHT includes avoiding risk factors, and practicing good oral hygiene especially brushing the posterior tongue. Many treatment modalities have been proposed till date like use of antifungals (Fluconazole), corticosteroids, third generation Cephalosporin- Cefditoren, vitamin preparations etc. Lifestyle modifications, including aggressive oral hydration are important and increased dietary consumption of raw fruits and vegetables may help improve this condition by facilitating the roughage on the tongue [7, 8]. Anecdotal use of antimicrobial therapies, topical triamcinolone acetonide, gentian violet, salicylic acid, vitamin B complex, thymol, and topical or oral retinoids (e.g., isotretinoin), as well as keratinolytics (podophyllin), topical 30% urea solution, and trichloroacetic acid have been reported in the literature. Sometimes, it exhibits self remission after stoppage of broad spectrum antibiotics. Gentle debridement with a soft toothbrush or tongue scraper to promote desquamation of the hyperkeratotic papillae. Topical application of baking soda or rinsing with diluted hydrogen peroxide solution may help improve desquamation of the keratinized filiform papillae and bleach the color [9, 10].

Conclusion

Antibiotic induced black hairy tongue is a common entity, though it can provoke anxiety episodes to patient and health care professional both. So, a comprehensive history of habits, examination, drug history review is essential as causes of BHT could range from simple poor oral hygiene to more sinister conditions like malignancy and immunocompromised conditions like HIV. Antibiotic induced BHT demands reassurance, promoting oral hygiene practice and regular follow up.

References

1.Nisa L, Giger R. Black hairy tongue. Am J Med. 2011;124:816–817.
2. Motallebnejad M, Babaee N, Sakhdari S, Tavasoli M. An epidemiologic study of tongue lesions in 1901 Iranian dental outpatients. J Contemp Dent Pract. 2008;9:73–80.
3.Thompson DF, Kessler TL. Drug-induced black hairy tongue. Pharmacotherapy. 2010;30:585–593.
4. Pigatto PD, Spadari F, Meroni L, Guzzi G. Black hairy tongue associated with long-term oral erythromycin use. J Eur Acad Dermatol Venereol. 2008;22:1269–1270.
5. Körber A, Voshege N. Black hairy tongue in an infant. CMAJ. 2012;184:68
6. Sheikh Z, Khan AS, Khan S. Lingua villosa nigra. Lancet. 2011;377:1183.
7. Jeong JS, Lee JY, Kim MK, Yoon TY. Black hairy tongue associated with erlotinib treatment in a patient with advanced lung cancer. Ann Dermatol. 2011;23:526–528.
8. Ramsakal A, Mangat L. Images in clinical medicine. Lingua villosa nigra. N Engl J Med. 2007;357:2388.
9. Aijazi I, Abdulla FM. Linezolid induced black hairy tongue: a rare side effect. J Ayub Med Coll Abbottabad. 2014;26(3):401–3.
10. Nakajima M, Mizooka M, Tazuma S. Black hairy tongue treated with oral antibiotics: a case report. J Am Geriatr Soc. 2015;63(2):412–3.