肉眼的血尿を契機に診断した全身性Wild-type ATTRアミロイドーシスの1例

Abstract

An 85-year-old woman visited our hospital with a complaint of asymptomatic gross hematuria. Cystoscopy showed a non-papillary sessile tumor about 3 cm in size. Magnetic resonance imaging (MRI) suggested invasion of surrounding fat tissue. Thoracoabdominal contrast-enhanced computed tomography (CT) showed no tumor of the upper urinary tract or metastasis. We diagnosed the tumor as bladder cancer cT3N0M0 and performed transurethral bladder tumor resection 22 days after her first visit. No tumor was found at the time of surgery. We resected a reddened area to include a muscle layer and performed random biopsy. Hematoxylin and eosin stain showed eosinophilic tuberous tissue that stained with Congo red around blood vessels in the subepithelial stroma and the muscle layer. There was no dysplasia in the bladder epithelium. Therefore, we diagnosed the case as bladder amyloidosis. Immunostaining of the amyloid subtype revealed transthyretin amyloid (ATTR) amyloidosis. Bence-Jones protein in urine was negative, M protein was not detected in serum protein electrophoresis, and serum amyloid A was at the threshold. Scintigraphy for 99m Tc pyrophosphoric acid was positive in the myocardium. No genetic disorder was detected. We concluded that it was systemic ATTRwt amyloidosis as above. The patient did not wish to be treated for the systemic amyloidosis. Thirteen months after surgery, the patient showed no signs of recurrence in the bladder. As cardiac function is a prognostic factor in systemic amyloidosis, we need to consider the possibility of systemic amyloidosis when diagnosing bladder amyloidosis.