A rare case of fibrohistiocytic hepatic inflammatory pseudotumor with cholecystocholangitis showing positive IgG4 staining.

Inflammatory pseudotumor (IPT) is a rare benign mass characterized by infiltration of inflammatory cells and proliferation of fibrous tissues. Consistent with increasing knowledge about IgG4-related disease (RD), it has been implicated in the etiology of hepatic IPT, which is pathologically classified into two categories with respect to the proportion of IgG4-positive plasma cells: fibrohistiocytic- and lymphoplasmacytic-type. A 66-year-old man was admitted for treatment of cholecystocholangitis. Incidentally, abdominal computed tomography (CT) revealed an ambiguous low-density mass within segment 4 (S4) of the liver. Magnetic resonance imaging (MRI) showed the typical images of hepatic IPT within S4. Together with CT and MRI imaging, we suspected hepatic IPT, and had the opportunity to biopsy the S4 lesion during surgery for cholecystitis. Histopathological examination of liver tissue showed diffuse fibrous tissues, dense lymphoplasmacytic infiltration, and obliterative phlebitis with no evidence of malignancy. Despite infiltration of IgG4-positive plasma cells, these histological findings corresponded with fibrohistiocytic-type hepatic IPT. Similarly, in the resected gallbladder, relatively abundant IgG4-positive cells were observed, but not entirely consistent with IgG4-RD criteria. Although IgG4 immunostaining can be useful for the classification of hepatic IPT, the present histological tissues were borderline condition defined by IgG4-RD criteria. This rare case of hepatic IPT suggests a future focus on the borderline histological features of IgG4-RD.

Early gastric cancer with lanthanum deposition mucosa by endoscopic submucosal dissection: a case report and literature review.

Lanthanum carbonate is used to prevent hyperphosphatemia in dialysis patients with chronic renal failure and generally recognized as poorly absorbed by the gastrointestinal tract. However, some clinical cases of lanthanum deposition in the stomach have been shown. In addition, few endoscopic images of lanthanum deposition have been reported, particularly with respect to early-stage gastric cancer. A 64-year-old man with 22 years history of dialysis was treated with lanthanum carbonate for 3 years. With screening esophagogastroduodenoscopy, he was diagnosed with intramucosal gastric cancer, surrounded by the specific endoscopic images of the lanthanum deposition, and underwent endoscopic submucosal dissection. Histopathologically, massive accumulations of macrophages containing fine, granular, eosinophilic materials were observed in the lamina propria. These eosinophilic depositions were present in the lamina propria of the non-tumor region, but not in that of the tumor region. The histological features were further identified as lanthanum phosphate deposition by scanning electron microscopy. This case indicates the clinical significance of lanthanum deposition associated with gastric cancer. It is further required to evaluate more endoscopic images of the gastric mucosa, especially intramucosal cancer, with lanthanum deposition.