Lanthanum carbonate (LaC) is used to prevent hyperphosphatemia in dialysis patients. It is commonly believed that there is little LaC absorption from the intestines. However, La deposition in the gastric mucosa, which we coined "gastric lanthanosis", was recently reported. We describe here the clinicopathological features of and a possible mechanism for gastric lanthanosis. This study included 23 patients with definite gastric lanthanosis. We extracted characteristic clinicopathological features of gastric lanthanosis by computed tomography (CT) imaging and endoscopic, histologic, electron-microscopic, and element analysis examinations. The Helicobacter pylori infection rate in the lanthanosis group was much lower than that among the general population. The clinicopathological features characteristic of gastric lanthanosis were mucosal high-density linear appearance by CT, reflective bright-white spots (BWS) by gastroscopy, eosinophilic histiocytes occasionally phagocytizing foreign materials by histology, and numerous electron-dense particles in the histiocytes. The particles had burr-like skeletons resembling La crystals. Gastric lanthanosis is an under-reported, but not a rare lesion. It is characterized by endoscopic BWS and histologic eosinophilic histiocytes in dialysis patients treated with LaC. The proposed mechanism for gastric lanthanosis is that LaC is dissolved by gastric juice, crystallized within the mucosa and is phagocytized by histiocytes.

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We report a case of ALK-positive renal cell carcinoma coincident with Hodgkin lymphoma. The patient was a 19 year-old-girl without sickle cell trait. The right renal tumor was discovered concomitantly with Hodgkin lymphoma (HL). After chemotherapy for HL, right nephrectomy was performed. Microscopically, the tumor showed a solid and focally pseudo-papillary growth pattern studded with tubular structures. Most tumor cells were small bland eosinophilic cells, but rhabdoid cells, vacuolated cells, pleomorphic multinucleated giant cells were also admixed. The variety of growth patterns and cell features led us to speculate a possibility of ALK-positive renal cell carcinoma (ALK + RCC). ALK was immunohistochemically positive, and fluorescence in situ hybridization analysis detected a split signal of the ALK gene. We examined previously reported partner genes (STRN, TPM3, VCL and EML4) by RT-PCR, but fusion gene was not detected. RCC showing solid or cribriform growth patterns with vacuolated cells with intracytoplamic lumina, rhabdoid cells, and mucus production indicates the possibility of ALK + RCC.

Background Diagnoses reflect clear cell morphologies when tumor cells have clear cytoplasm in many organs, and the nature of such clear cells is typically identified. Colorectal tubular adenoma or adenocarcinoma, conversely, rarely show clear cells, the reason for which remains uncertain. We report 2 colon tumors with clear cell components (Case 1: adenoma; Case 2: adenocarcinoma) and investigate the nature of the clear cells. Case presentation Case 1 was a 75-year-old man with a superficial elevated polyp detected in the rectum for whom endoscopic submucosal dissection was performed. Microscopically, 10% of the tumor showed dysplastic columnar epithelium with clear cytoplasm forming tubular structures accompanied by conventional tubular adenoma. Case 2 was a 58-year-old man with a pedunculated polyp found in his sigmoid colon for which polypectomy was performed. Microscopically, 90% of the tumor showed dysplastic columnar epithelium with clear cytoplasm forming fused glands or cribriform structures adjacent to the ordinal tubular adenocarcinoma. In both cases, clear and ordinary tumor cells were negative for CK7 and positive for CK20 and CDX2, consistent with findings of colorectal origin. Different results were found for CEA and CD10 staining. CEA was positive on the luminal side of the conventional area in contrast diffuse cytoplasmic staining of the clear cell area in both cases. CD10 was only positive for the clear cell component of case 2. The clear cell components were negative for Periodic acid-Schiff (PAS), Alcian blue, and mucicarmine staining and AFP immunohistochemistry. An ultrastructural examination found multiple cytoplasmic lipid-like vacuoles in the clear cell component that were predominantly negative for adipophilin by immunoelectron microscopy. Conclusions We investigated tubular adenoma and tubular adenocarcinoma with clear cell components. The accompanying conventional tubular adenoma or adenocarcinoma cells helped us to evaluate the atypia of the clear cells. Diffuse cytoplasmic staining of CEA and CD10 suggested that the clear cell component might harbor malignant potential. We were unable to verify the well-known causes of clear cytoplasm, such as an accumulation of glycogen, lipid, or mucin and enteroblastic differentiation. The causes of clear cells in the colorectal region remain uncertain; however, possible explanations include autolysis and carbohydrate elution.

Salivary gland cancers (SGCs) are diagnosed using histopathological examination, which significantly contributes to their progression, including lymph node/distant metastasis or local recurrence. In the current World Health Organization (WHO) Classification of Head and Neck Tumors: Salivary Glands (5th edition), malignant and benign epithelial tumors are classified into 21 and 15 tumor types, respectively. All malignant tumors have the potential for lymph node/distant metastasis or local recurrence. In particular, mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (AdCC), salivary duct carcinoma, salivary carcinoma, not otherwise specified (NOS, formerly known as adenocarcinoma, NOS), myoepithelial carcinoma, epithelial–myoepithelial carcinoma, and carcinoma ex pleomorphic adenoma (PA) are relatively prevalent. High-grade transformation is an important aspect of tumor progression in SGCs. MEC, AdCC, salivary carcinoma, and NOS have a distinct grading system; however, a universal histological grading system for SGCs has not yet been recommended. Conversely, PA is considered benign; nonetheless, it should be cautiously treated to avoid the development of metastasizing/recurrent PA. The aim of this review is to describe the current histopathological aspects of the prognostic factors for SGCs and discuss the genes or molecules used as diagnostic tools that might have treatment target potential in the future.