Bosentan - a previously unrecognised cause of facial telangiectasia.

Annals Academy of Medicine Dear Editor, Bosentan is an endothelin-1 (ET-1) receptor antagonist approved for the treatment of pulmonary artery hypertension (PAH). Although fl ushing is a documented side effect of bosentan, the diagnosis can mimic other drug rashes and medical conditions where facial telangiectasis and/or fl ushing are prominent presentation. We present a 76-yearold woman complaining of fl ushing with gradual increase in redness. She had been diagnosed with PAH several years ago secondary to a thromboembolic event and had been taking bosentan (Tracleer) for the past 4 years. She described the redness of the face appearing around the same time period. The redness is more prominent 15 to 30 minutes after taking the drug. The fl ushed effect, accompanied with tingling, lasted for about 5 to 10 minutes. Treatment with oral minocycline or topical metronidazole gel had not improved her rash. Clinically, she was frail with evidence of sun damaged skin on exposed areas (Fig. 1). She had blotchy redness on both cheeks and nose. There was telangiectasia, but no papules or pustules. There was no rhinophyma or swelling of eyelids. Evidence of Poikiloderma of Civatte was also absent. She had been investigated for altered bowel habits but denied frank diarrhoea. Colonoscopy was not performed due to poor lung condition. Investigations were negative for 24 hour urinary excretion of 5 hydroxy-indole-acetic acid (5HIAA), and she had a normal abdominal ultrasound examination and liver function tests. ANA (Antinuclear Antibody test) showed a speckled pattern at a titre of 1/160. A differential diagnosis of rosacea, poikiloderma and drug induced erythema was considered. The differential diagnosis of carcinoid syndrome was also considered in this patient because of her intermittent fl ushing, persistent erythema in the form of facial telangiectasis and the recent history of altered bowel habits. As the tests for carcinoid syndrome were negative, and that fl ushing was aggravated in the same areas whenever she took bosentan, we concluded that her condition was secondary to bosentan. The main adverse events of bosentan are moderate and transient increase in transaminase levels. Other side events Bosentan – A Previously Unrecognised Cause of Facial Telangiectasia