Case presentation
A 73-years-old man had been on peritoneal dialysis for 9 years for
chronic renal failure due to immunoglobulin A nephropathy and had
switched to hemodialysis 3 years before the operations.
He had been taking lanthanum carbonate for seven years. Several months
after lanthanum carbonate initiation, regular endoscopy revealed white
granular lesions on the gastric mucosa at the gastric body and fundus
(Fig.1-A). A biopsy of these lesions revealed chronic active
inflammation with regenerative epithelium, intestinal metaplasia, and
lanthanum deposition. Regular annual endoscopy revealed that these
lesions had grown, changed morphologically, and spread gradually
(Fig.1-B), but they showed no malignancy. Two months before the
operation, regular endoscopy revealed a gradually growing, reddish, and
elevated mucosa surrounded by white granular mucosa in the gastric
antrum (Fig.2-A). Narrow band imaging (NBI) showed no signs of
malignancy, such as an irregular microvascular pattern (Fig.2-B), but
histological examination revealed well-differentiated adenocarcinoma.
The clinical stage was T1bN0M0 stage I based on the TNM classification
specified by the International Union Against Cancer (UICC). The boundary
between the adenocarcinoma and mucosal changes with lanthanum deposition
was unclear by endoscopy with NBI, and neoplastic lesions seemed to be
spread around the gastric body. Therefore, we planned to perform a
surgical operation to achieve curative resection and laparoscopic distal
gastrectomy with lymph node dissection. Histopathological examination
revealed a well-differentiated tubular adenocarcinoma, which was limited
to the antrum surrounded by lanthanum nodules (Fig.3-A). The tumor was
limited to the mucosa at the gastric antrum, and the pathological stage
was T1aN0M0 stage I. Lanthanum deposition was observed in the lamina
propria of the carcinoma and gastric mucosa (Fig.3-B). Histological
alterations, such as glandular atrophy and hyperplasia, were also
observed. The resected lymph nodes also included lanthanum deposits
eaten by macrophages (Fig.3-C). In the interstitium of cancerous and
non-cancerous lesions, lanthanum was mostly eaten by macrophages that
expressed CD68 (Fig.4-A, B).