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Melanosis of the oesophagus in a Western patient

Melanosis of the oesophagus is an uncommon lesion and a rarely described endoscopic finding in Western patients. This rarity prompts us to report this case. A 75-year old French man had upper gastrointestinal endoscopy for epigastric pain. The duodenum was normal. The stomach showed mild mucosal inflammation of the antrum. In the oesophagus, two dark-bluish, flat and sharply delineated areas (measuring together about 25mm in diameter) were noted 200 mm below Killian’s line (Figure 1). Several smaller ‘satellite’ pigmented spots were also present. Biopsies were taken from one of the two main lesions and from one satellite spot. Careful examination of the skin, oral cavity and ano-genital region disclosed no other pigmented lesion. There was no history of mole excision. Haematoxylin and eosin sections showed coarse brownish-black pigment within the cells of the basal layer of the squamous epithelium (Figure 2). The pigment stained positive with the Masson–Fontana method, was bleached completely with hydrogen peroxide and was negative with both PAS and Perls’ methods. The pigmented melanocytes showed positive immunostaining with protein S-100 and HMB45 antisera (Dako). There was no cellular atypia. The underlying lamina propria contained pigment-laden macrophages and was devoid of inflammatory reaction. Considering the large number of upper gastrointestinal endoscopies performed daily, publications on melanosis of the oesophagus are relatively few. Papers have been mostly concerned with the identification of melanocytes in apparently normal-looking oesophagi from unselected autopsies, i.e. microscopic melanosis. In this context, the presence of melanocytes in seemingly normal oesophageal mucosa has been reported as 3.77% to 4% in Western patients and 7.7% to 8% in the Japanese population. The term ‘melanosis of the oesophagus’ has also been used for endoscopically visible pigmented lesions of the oesophageal mucosa, i.e. macroscopic melanosis, and the subsequent histological demonstration of their melanocytic nature in biopsy material. Endoscopic or macroscopic melanosis has also been described in 25% to 30% of surgical specimens of oesophagus containing primary malignant melanoma. Our case corresponds to the endoscopic or macroscopic form of melanosis of the oesophagus in a Western patient, an apparently extremely rare situation judging from the scarce literature. This case and other similar ones raise two questions. First, how can one explain the presence of melanocytes in the oesophagus? During embryogenesis, melanocytes (melanoblasts) arise in the neural crest and migrate to other sites such as epidermis, hair follicles, uvea, choroid, leptomeninges, substantia nigra, oral cavity and nasopharynx. Thus, it seems conceivable that melanocytes could reach other ‘ectopic’ situations such as the oesophageal mucosa. An alternative possibility is that melanocytes are formed in the oesophagus as the result of differentiation from totipotential cells in the basal layer of the squamous Histopathology 1997, 30, 498–499