Unusual cutaneous adverse effect of carbamazepine: A case of drug-induced vitiligo

INTRODUCTION

Vitiligo is a chronic autoimmune skin disease with a global prevalence of 0.5–2%, with the highest rates in the Indian subcontinent, affecting 8.8% of the population.¹ The autoimmune hypothesis explains the pathogenesis of vitiligo.² Drug-induced vitiligo is a rare adverse effect associated with carbamazepine. Carbamazepine, an anticonvulsant, is a sodium channel blocker also used as a first-line therapy in trigeminal neuralgia. The most common adverse effects include dizziness, drowsiness, ataxia, nausea, and vomiting.³ This study presents a rare case report of vitiligo associated with carbamazepine use.

CASE REPORT

A woman in her mid-30s with a two-year history of trigeminal neuralgia was prescribed carbamazepine 200 mg twice daily. She had no prior history of skin diseases or autoimmune diseases. After two years of therapy, she noticed the gradual onset of hypopigmented patches on the lower lip and adjacent perioral region, characteristic of vitiligo. After obtaining written informed consent from the patient, the pictures were taken. The affected area exhibited complete depigmentation, with no signs of erythema, scaling, or inflammation, indicating a non-inflammatory loss of melanocytes [Figure 1]. The pigmentation surrounding the affected area is normal. There were no signs of secondary infection, atrophy, or scarring. The location of the lesion in the perioral region suggests involvement of mucocutaneous areas, which can be cosmetically distressing considering her age and may impact the patient’s quality of life. The laboratory investigations ruled out thyroid and autoimmune disorders. Multiple sclerosis is often associated with vitiligo, and it was ruled out based on the clinical examination. The dermatologist confirmed it as a case of acrofacial vitiligo, likely associated with carbamazepine, confirmed through a Wood’s lamp examination, which highlighted depigmented lesions with a distinct milky-white appearance. Carbamazepine was discontinued, and the patient was started on gabapentin 300 mg orally at bedtime. The patient was reviewed after 3 months, and the hypopigmented patches began to pigment, indicating reversibility [Figure 2]. The patient remains under follow-up with no recurrence of symptoms.

Close

Figure 1:

Hypopigmented patches after carbamazepine therapy. Original picture obtained after patient’s consent.

Export to PPT

Close

Figure 2:

Repigmentation after discontinuation of carbamazepine. Original picture obtained after patient’s consent.

Export to PPT

In this case, the patient developed an adverse reaction 2 years following the administration of carbamazepine. Naranjo’s algorithm was used to determine a plausible reaction due to carbamazepine. The following criteria were considered:

DISCUSSION

This case report highlights a rare occurrence of carbamazepine-induced vitiligo in a patient on long-term therapy for trigeminal neuralgia. Unlike a previously reported case where the patient developed erythema and widespread redness before progressing to depigmentation within 2 weeks of drug initiation, our patient exhibited a gradual onset of hypopigmented lesions after 2 years of treatment without preceding inflammation.^4,5 The absence of erythema, scaling, or other inflammatory signs suggests a non-inflammatory loss of melanocytes. A probable causal link was established using the Naranjo scale (score of 7), further supported by lesion repigmentation after discontinuing carbamazepine.

CONCLUSION

Given the prevalence of vitiligo in India, clinicians should closely monitor patients undergoing prolonged carbamazepine therapy for any dermatological changes. Early detection and drug withdrawal can lead to symptom reversal, underscoring the need for further research on drug-induced vitiligo.