A 53-year-old woman was referred to gastroenterology with a 3-week history of dyspepsia and fatigue. She had no prior history of reflux symptoms, altered bowel habit or weight loss. There was no significant medical history and no history of alcohol or tobacco consumption. Physical examination was normal, and initial blood tests revealed a haemoglobin of 9.9 g/dl and a ferritin of 18 μg/l, consistent with iron-deficiency anaemia. An oesophagogastroduodenoscopy was performed and a linear blue/black pigmented macular lesion was noted in the oesophagus at 28 cm, from which multiple biopsies were taken, in addition to oesophagitis (figure 1). Histopathology of the oesophageal biopsies showed squamous mucosa, with an increase in melanocytosis and dendritic processes spreading around adjacent epidermal cells, consistent with a diagnosis of oesophageal melanocytosis (figure 2). Differential diagnosis includes benign nevi, blue naevus and primary malignant melanoma because melanin deposition is often the main feature in these lesions.1 Addison's disease, anal melanoma and Laugier–Hunziker syndrome may also explain pigmented lesions found at endoscopy.1 2 Some authors have suggested oesophageal melanocytosis to be a precursor for oesophageal melanoma and carcinoma.3 Oesophageal melanocytosis is rare and is a histological diagnosis. Our case is the first from the UK to be considered for publication, and there are currently no follow-up studies to establish guidelines for management, including surveillance. We opted to commence the subject on a proton-pump inhibitor, with follow-up endoscopy within 18 months. Recognition of this lesion at endoscopy is vital, given the potential differential diagnoses.