Marked regression of abdominal fat amyloid in patients with familial amyloid polyneuropathy during long-term follow-up after liver transplantation

To elucidate whether the amount of tissue-deposited amyloid in familial amyloid polyneuropathy (FAP) patients decreases or increases over the long-term course after liver transplantation (LT), we examined changes in histopathological and biochemical characteristics of abdominal fat amyloid in the transplanted patients with a postoperative history of more than 10 years. Using a series of aspirated abdominal fat tissues from 6 FAP patients with transthyretin (TTR) Val30Met variant, the severity of amyloid deposits was examined and the composition ratio of wild type-to-variant TTR in fat amyloid was assayed by liquid chromatography-ion trap mass spectrometry (LC-MS/MS). Histopathological examination of abdominal fat tissues demonstrated a significant decrease or disappearance of amyloid deposits in all 6 patients. On LC-MS/MS analysis, the contribution of wild-type TTR to the composition ratio in amyloid fibrils was markedly increased in all patients after LT. This is the first report showing pathological evidence that deposited amyloid in FAP patients with long posttransplantation courses can gradually regress or disappear.