Purpose: Urinary citrate is a potent inhibitor of renal stone formation. Its excretion is regulated by Na + /dicarboxylate cotransporter-1 (NaDC-1), which is expressed on the apical membrane of renal proximal tubules. Many patients with calcium urolithiasis exhibit hypocitraturia, however, the mechanisms are not perfectly understood. We examined whether or not the I550V polymorphism in human NaDC-1 gene (hNaDC-1) influenced urinary citrate excretion. Materials and methods: I550V polymorphism was investigated in 105 patients with recurrent renal calcium stone formation (RSF) and 107 age-matched healthy volunteers with non-renal stone formation (NSF), using polymerase chain reaction (PCR) restriction fragment length polymorphism analysis and two 24-h urine samples. Results: Overall and in the RSF groups, subjects with a BB (homozygous for the digested Bcl-I allele) genotype exhibited a significantly lower urinary citrate excretion level than subjects with a bb (homozygous for the undigested allele) genotype. Genotype distributions between subjects with hypocitraturia and normocitraturia were significantly different, with the BB genotype being more frequently observed in subjects with hypocitraturia -both overall and in each of the RSF and NSF groups. Although the BB genotype was observed more frequently in the RSF group than in the NSF group, no statistical differences among the distributions of the three genotypes (BB, Bb [heterozygous] and bb) were observed between the RSF and NSF groups. Conclusion: These results suggest that the B allele of I550V polymorphism of hNaDC-1 may be associated with a reduction in urinary citrate excretion and contribute to hypocitraturia in recurrent renal stone formers.

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Background: While the incidence of calcium urolithiasis increases, the precise mechanism of calcium oxalate stone formation is still controversial. Is the composition of a recurrent calcium oxalate stones always the same as previous ones? There are few reports that specifically address the question by study of sequential changes of the composition of recurrent calcium calculi. Method

A rare case of chondroma of the diaphragm is reported. The patient was a 23-year-old female who had had recurrent upper abdominal pain for 4 years. Her symptoms and physical findings on admission suggested an intra-abdominal tumor. Roentgenological study disclosed a mass with a thick calcified wall in the upper abdomen. Laparoscopy revealed a multinodular white mass protruding from the left hemidiaphragm. The mass was surgically enucleated from the diaphragm. The resected tumor had a thick, calcified wall and a narrow lumen containing colorless fluid. Microscopic examination disclosed a hyaline chondroid matrix with mature chondrocytes, as well as extensive ossification. Primary tumor of the diaphragm is an uncommon disease. Only one case of chondroma of the diaphragm has been reported in the literature. Laparoscopy was useful in confirming the tumor's location and in speculating on its nature.

The case of a 63-year-old woman with a relatively rapidly growing angiomyolipoma (AML) originating from the right renal sinus is presented. The tumor had enlarged to more than fivefold in volume (7.4 × 6.7 × 10.1 cm) in the 7 years following its detection (5.6 × 3.4 × 4.6 cm) and had significantly pushed aside the duodenum and the inferior vena cava. The tumor was surgically resected together with the right kidney, and pathological examination revealed AML originating from the renal sinus. An AML involving or originating from the renal sinus is exceedingly rare; only 14 cases have been reported. Rapidly growing AMLs of the renal sinus are difficult to differentiate from liposarcoma because of similar findings in imaging studies. It should be noted that AML of the renal sinus can be a differential diagnosis of retroperitoneal fatty mass. Furthermore, an enlarged AML in the renal sinus may push aside other organs, such as the ileum, pancreas, and major vessels. Clinicians should determine whether these patients should be placed under active surveillance or be treated with invasive measures, such as radical nephrectomy.