Butterfly rash, dental staining & painful nails in a child

A four year old pre-school girl child† presented to the dermatology outpatient department of the Postgraduate Institute of Medical Education & Research, Chandigarh, India, in December 2017 with a well-defined, erythematous rash spanning her nose and malar area and extending till lateral cheeks. Nasolabial folds were spared (Fig. A & B). The lesions started around one month back, gradually progressed and were associated with photosensitivity and mild itching. Further examination revealed tender nails and crescent-shaped separation of nail plate from the nail bed (onycholysis) with whitish-brown discoloration, most pronounced on the thumb, index and middle fingers (Fig. C). Nail folds were normal. Examination of the oral cavity demonstrated brown-black dental discoloration (Fig. A & B). There were no systemic symptoms such as fever, flushing, Raynaud's phenomenon, arthralgia, muscle weakness, dyspnoea, dysphagia, oral/genital ulcers, abdominal pain, frothy urine, seizures, diarrhoea or alopecia. Her antinuclear antibody profile was normal.

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Figure (A) An erythematous, scaly, butterfly-shaped rash affecting the nose and cheeks. Rash was extended to the temporal areas and is prominently sparing the nasolabial fold. (B) Front view of the face demonstrating the prominent brown-black dental staining (blue arrow) and sparing of nasolabial fold (red arrow). (C) Distal separation of nail plates from the nail bed is visible on thumb, index and middle fingers (the digits having maximum exposure to sun, marked with blue arrow), associated with brownish discoloration and erythema.

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Her medical history was significant for intake of doxycycline for the past two months for an episode of conjunctivitis. In view of the constellation of symptoms including photosensitive malar rash (in absence of any systemic symptoms), dental discoloration and tender photo-onycholysis, a diagnosis of acute phototoxicity secondary to intake of doxycycline was made. Doxycycline was stopped, and the child was advised broad-spectrum sunscreens, beta-carotenes and dark-coloured nail varnishes. Her skin lesions improved after a month, but dental staining was persistent (although decreased) after three months. The child was lost to follow up after three months.

The present case highlighted two important findings. First the drug (doxycycline in this case)-induced phototoxicity can present with malar rash (thus simulating acute lupus) and it is rewarding to examine nails and teeth. Second, the time of onset can vary from a few days after ingestion of doxycycline to many days after stopping the drug, especially to manifest nail changes.