Giant Hepatomegaly with Spleno-testicular Enlargement in a Patient with Apolipoprotein A-I Amyloidosis: An Uncommon Type of Amyloidosis in Japan.

Hereditary systemic amyloidosis aside from transthyretin-related familial amyloid polyneuropathy is quite uncommon in Japan. We herein report a sporadic case of hereditary apolipoprotein AI (apoAI) amyloidosis. The patient was a 43-year-old Japanese man who exhibited marked hepatomegaly with spleno-testicular enlargement. While he was initially thought to have primary AL amyloidosis, a proteomics analysis revealed that the amyloid was composed of variant apoAI with an E34K variant. To date, only one patient with apoAI amyloidosis has been reported in Japan. However, our study suggests that more patients may be present in Japan, and the majority may have been diagnosed with other types of amyloidosis due to its clinical similarity.