Sir, a 70-year-old Caucasian female was assessed at our oral medicine department due to concerns from her GDP who noticed unusual pigmentation on the hard palate whilst assessing for the provision of new dentures.

The patient had a previous diagnosis of rheumatoid arthritis with secondary Sjögren's syndrome affecting the eyes and the oral mucosa. Her medication list consisted of hydroxychloroquine, omeprazole, ciclosporin eye drops and saliveze mouth spray. The patient also had a long history of smoking fewer than ten cigarettes a day. We gave smoking cessation advice and she agreed to stop smoking.

Upon examination the mucosa appeared moist and healthy with blue pigmentation affecting the hard palate only (Fig. 1). Differential diagnoses of drug induced pigmentation and smoker's melanosis were considered, amongst others. To confirm the diagnosis, an incisional biopsy was carried out and the histological report confirmed hemosiderin pigmentation related to hydroxychloroquine use.

Fig. 1
figure 1

Discolouration of the hard palate seen in the patient taking hydroxychloroquine

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Hydroxychloroquine, known as an antimalarial drug, is also indicated for the management of rheumatoid arthritis as well as systemic and discoid lupus erythematosus. Side effects can include gastrointestinal disturbances and skin reactions, including hyperpigmentation of the skin which can be mistaken for bruising.1,2

We informed the patient's rheumatologist of the diagnosis and subsequently their hydroxychloroquine prescription was amended from 200 mg once per day to 200 mg three times a week. The GDP was reassured that the denture provision could safely commence. Drug-induced pigmentation has been long documented in the literature. For example, it can occur due to melanin accumulation which may be exacerbated by sunlight, accumulation of the drug itself which may be able to form a complex with melanin, or by iron deposits in an area of vessel damage. Other drugs known for causing skin pigmentations include NSAIDs, amiodarone, tetracyclines, antipsychotics and heavy metals.3