Abstract
Melanosis involving the duodenum and stomach is extremely rare. This report describes endoscopic, light and electron microscopic and histochemical studies of five patients with melanosis of the duodenum, one of them complicating melanosis of the stomach. Melanosis was extended in the entire duodenum and upper jejunum in Case 1(Figure 1 and 2). The melanosis disappeared after the cessation of hydralazine and captopril (Figure 3). In Case 2, melanosis was observed in the pericardial region of the stomach and colon not only in the duodenum (Figure 6). In Case 3, 4 and 5, melanosis was seen in the bulb and second portion of the duodenum (Figure 9, 11 and 12). Histological examination revealed accumlations of dark-brown pigments in the upper lamina propria of the gastric and duodenal biopsies, occurring mostly in macrophages (Figure 4-a, 7-a and 10-a). The pigment in Case 1, 2, 4 and 5 had a positive reaction with special stains for melanin (Figure 4-b and 7-b) and negative with stains for iron. The pigment in Case 3, however, was positive for the iron stain (Figure 10-b) but negative for the melanin stain. Electron microscopic studies of the gastric and duodenal melanosis revealed irregular shaped electron-dense materials in the lysosomes of the macrophages (Figure 5 and 8). Our study shows that the occurrence of pigmentation in melanosis of the stomach is identical to that seen in the duodenum. The nature and source of the pigment is still contraversial. On the basis of the history of our patients and cases reported in the literature, it is conceivable that the possible sources of the pigment are medications that contain a benzen ring, ferrous sulfate or hemorrhage in the gastrointestinal tract. Despite the well-documentated histochemical characteristics and ultrastructure of the pigment, its precise chemical structure and mode of the formation need further investiga-tions.
