Correspondence Address:
Kaliaperumal Karthikeyan
Department of Dermatology, Venereology, and Leprosy, Sri Manakula Vinayagar Medical College and Hospital, Puducherry 605107
India

Full Text



Black hairy tongue (BHT) is a benign, self-limiting, acquired disorder. It occurs with the presence of abnormal hypertrophy and elongation of filiform papillae, which classically affects the dorsum of the tongue.[1] Linezolid is an antimicrobial drug, which belongs to the oxazolidinone group. Antibiotic-resistant Gram-positive bacteria are responsive to linezolid. The most common side effects of linezolid are headache, nausea, vomiting, and diarrhea. If linezolid is used for more than 2 weeks, patients may have neuropathy, bone marrow suppression, and rarely BHT.[2] We present a rare case of linezolid-induced BHT.

An 18-year-old female presented with blackish discoloration of the dorsum of the tongue since 4 days following oral linezolid 600 mg twice daily for 1 month duration for urinary tract infection. On examination of the oral cavity, blackish discolouration was noted on the dorsal surface of the tongue [Figure 1]. KOH examination of the tongue scraping was negative. A clinical diagnosis of BHT was made. To determine the association of linezolid and BHT in this case, Naranjo ADR probability scale was used, and the score was 5, which is a probable adverse reaction.[3] Linezolid was stopped and the patient was advised to do regular brushing of the tongue using a soft toothbrush and antiseptic mouthwash twice daily. In addition, the patient was started on probiotics. A follow-up visit 4 weeks later showed complete resolution of discoloration [Figure 2].{Figure 1} {Figure 2}

The name black hairy tongue is a misnomer as the condition presents with hairy carpet like black lingual growth. It may also be seen in different colors such as yellow, blue, green, and brown or may not be pigmented at all. Various names have been given to this disorder such as keratomycosis linguae, hyperkeratosis of the tongue, melanotrihia lingua, nigrites linguae, and lingua villosa nigra.[1] Most of the patients are asymptomatic, whereas few experience burning sensation or tickling of the tongue, nausea, dysgeusia, and halitosis. Cosmetic problem is the main concern in BHT-affected individuals.[2]

The pathogenesis of BHT is not well understood. The predisposing factors often associated with BHT are poor oral hygiene, smoking, excessive intake of coffee, black tea, and alcohol. Use of oxidizing mouthwashes, iv drug use, substance abuse, and xerostomia may also attribute to this condition.[1] BHT is also caused by the usage of various drugs [Table 1].[1],[4] Patients receiving radiation therapy to head and neck, HIV, trigeminal neuralgia, amyotrophic lateral sclerosis, or malignancy are all at risk of developing BHT.[1]{Table 1}

These predisposing factors lead to inadequate desquamation on the dorsum of the tongue, resulting in the accumulation of the keratin layer. This plays a major role in the formation of hair-like projection in BHT. The elongated filiform papillae present in BHT trap the food particles, fungi, and bacteria. The pigmentation in BHT is due to the oxidation of porphyrin by the trapped bacteria.[4]

Clinically, BHT may be confused with pseudo-hairy tongue. The latter is due to drugs, tobacco, and food, which presents as black-colored tongue without elongation of filiform papillae. Oral hairy leukoplakia, pigmented fungiform papillae of the tongue, and acanthosis nigricans are other differential diagnoses, which should be ruled out.[1]

Diagnosis is based on the history of precipitating factors and clinical examination of the oral cavity. Microscopic examination is found to be useful in the diagnosis. Co-infection with bacteria or fungi can be ruled out by a culture test. Biopsy should be done only in doubtful cases.[1]

The treatment is discontinuation of any inciting agents. Good oral hygiene should be maintained by cleansing the tongue with a soft toothbrush. Many drugs including topical 50% trichloroacetic acid, 40% urea solution, triamcinolone acetonide, gentian violet, vitamin B complex, salicylic acid, thymol, baking soda, and retinoids have been found to be effective in the treatment of BHT. Systemic retinoids can also be given. In case of co-infection with Candida albicans, topical nystatin and fluconazole are used.[5] Probiotic and yogurt supplementation are shown to be helpful in BHT.[1]

Although BHT due to oral linezolid is rare, the treating physician should be aware of the side effects. The physician should educate the patient on the importance of oral hygiene in patients on antibiotics.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References