Case reports: pseudomelanosis duodeni: association with systemic hypertension.

Two male patients with mild gastrointestinal bleeding had peculiar dark pigmentation of their duodenum on upper endoscopy. These pigmented lesions were still present 3 months after the original endoscopy and after resolution of all other mucosal lesions. Both patients had other medical problems, including hypertension. They have been on multiple antihypertensive medications for many years. Biopsies of these duodenal lesions showed the pigment to be present inside the macrophages found in the lamina propria and in between the epithelial cells. Electron microscopy revealed a lysosomal localization of this pigment. This melanin-like pigment proved to contain varying amounts of iron, sulfur, and calcium. This pigmentation is closely associated with systemic hypertension, even in the pediatric population.