[A case of a primary localized amyloidosis (amyloid tumor) of the renal pelvis and ureter].

A 62-year-old woman complaining of asymptomatic hematuria was hospitalized. Although a cytologic examination of the urine was negative, abnormal findings in the right renal pelvis by DIP, RP and CT led us to suspect a pelvic tumor, and a right nephroureterotomy was performed. Light microscopy revealed deposits of amorphous, eosinophilic material in the pelvis and proximal portion of upper ureter, however tumor cells were not found. Electron microscopy revealed that these materials were aggregates of linear, non-branching fibrils, measuring about 8 nm in diameter. Histochemically, these were seen to be consistent with amyloid, producing an apple-orange birefringence with Congo red staining under a polarized light. Alkali Congo red staining after pretreatment of KMnO4 demonstrate that this amyloid protein was composed largely of AA protein in addition to lesser amounts of non-AA protein, and a primary localized amyloidosis (amyloid tumor) was diagnosed. A clinicopathologic study that was performed on 12 cases of primary localized amyloidosis of the pelvis, including our case, also is reported.