Discussion
We report a rare case of laparoscopically resected gastric adenocarcinoma with concurrent lanthanum deposition. In this case, we chose surgical resection because of the ambiguous boundary between malignant tissue and mucosal changes with lanthanum deposition.
There are a few reports of surgically resected gastric cancer with lanthanum deposition, as summarized in Table 1.2,12Yabuki et al. reported a summary of three patients with gastric cancer accompanied by lanthanum deposition who underwent surgical resection.11 They reported that the duration of lanthanum administration ranged from 3 to 36 months, and the depth of cancer was the entire submucosa (range: 1.5–5 mm). Lanthanum deposition was identified in the regional lymph nodes to some degree in all three cases. These findings support the hypothesis that lanthanum malabsorption in the gastric mucosa leads to other lymph nodes via lymphatic flow. Tonooka et al. reported a case of multiple but early gastric cancers in a patient with lanthanum deposition who underwent subtotal gastrectomy after 7 months of drug use.12 In this case, many macrophages with lanthanum deposits accumulated in the lamina propria of the gastric wall and tumors, which was confirmed by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-ESD). They also showed intestinal metaplasia associated with lanthanum deposition and considered that altered tight junction proteins may lead to its permeability, possibly resulting in lanthanum deposition. Our case showed mucosal atrophy and metaplasia, including a cancerous lesion at the gastric antrum, with CD68-positive macrophages containing lanthanum deposits, which were also identified in regional lymph nodes.
In gastric adenocarcinoma concurrent with lanthanum deposition, the findings of lanthanum deposition by endoscopy are occasionally similar to carcinoma, and it can be difficult to mark the boundary of the neoplasm and lesions. The findings of lanthanum deposition have been usually described as shiny, bright white, and of varied sizes and shapes, from small and flat to elevated plaques.9Gastric carcinoma is also known to show various findings with endoscopy. In previous reports, early gastric cancer with lanthanum deposition was observed as a depressed area surrounded by annular whitish lanthanum-deposited mucosa8,13 and resected by endoscopy. Yabuki et al. summarized the cases of three patients with concurrent gastric cancer who received laparoscopic distal gastrectomy, but the endoscopic findings showed a clear boundary between malignant tissue and the surrounding mucosa with lanthanum deposition.11 Tonooka et al. also reported concurrent gastric cancer with lanthanum deposition in patients receiving subtotal gastrectomy, but they did not refer to the endoscopic findings.12 The usefulness of magnified imaging using NBI was recently reported, and it shows irregular vascular and pit structures of malignant tissues.13 However, in this case, the carcinoma was detected within multiple reddish granular areas with lanthanum deposition without any specific malignant findings with NBI, and it was difficult to find the boundary between the neoplasm and lanthanum deposition. Therefore, we considered the possibility of non-curative resection with endoscopy and other lurking regions, and the carcinoma was surgically resected. Furthermore, using laparoscopy made it possible to observe the whole serous membrane of the stomach, nearby lymph nodes, and other organs in detail.
The relationship between malignancy and lanthanum deposition in gastric cancer concurrent with lanthanum deposition is unknown. Yabuki et al. examined the effect of oral administration of lanthanum carbonate on gastric mucosa in a rat model.11 They showed that it caused various histologic alterations such as glandular atrophy, the proliferation of mucous neck cells, and intestinal metaplasia, and concluded that these mucosal injuries, named lanthanum gastropathy, could potentially induce abnormal cell proliferation or neoplastic lesions. In sequential changes of the gastric epithelium due to lanthanum gastropathy, it becomes difficult to identify the boundary between the neoplasm and mucosal changes without malignancy, and surgical resection is recommended in such cases.
We present a rare case of gastric adenocarcinoma concurrent with lanthanum deposition in a patient who underwent laparoscopic distal gastrectomy due to ambiguous borders. In our case, it is difficult to mark the border between the neoplasm and lesions due to lanthanum deposition, and we performed surgical resection to secure a curative margin. The clinical significance and relationship between neoplasm and lanthanum deposition have been suggested, but enough evidence has not been reported. Our results add to this growing body of data and will aid in clarifying this relationship.
Table.1 Summary of surgically resected gastric cancer with lanthanum deposition, including this case