[An unusual cause for kidney transplantation]

Systemic amyloidoses are a heterogeneous group of rare diseases characterized by deposition of misfolded proteins. Amyloid A (AA) amyloidosis results from chronic inflammatory processes, with autoinflammatory diseases-particularly familial Mediterranean fever (FMF)-representing one of the most common causes. Genetic autoinflammatory diseases should be considered in the differential diagnosis, especially in patients from high-prevalence regions with unexplained renal insufficiency.

The case of a 50-year-old female patient of Armenian origin who underwent kidney transplantation in 2022 for end-stage renal failure of unknown etiology is reported. Despite adequate immunosuppression, she developed progressive graft dysfunction with increasing proteinuria. In addition, persistently elevated serological inflammatory markers were observed, but without accompanying clinical symptoms. Repeat transplant biopsy ultimately revealed glomerular amyloid deposits on Congo red staining, and immunohistochemistry confirmed AA amyloidosis. Genetic analysis demonstrated compound heterozygosity in the Met694Val/Val726Ala (MEFV) gene. A diagnosis of familial Mediterranean fever type II with systemic amyloidosis was established, and anti-inflammatory therapy with colchicine was initiated. Type II FMF typically follows a primarily subclinical course and first manifests through the development of systemic, most commonly renal, AA amyloidosis.

This case highlights the need for a thorough differential diagnostic work-up in progressive renal failure of unknown etiology combined with persistent serological inflammation. In end-stage renal failure of unknown cause and systemic inflammatory signs, rare conditions such as AA amyloidosis should also be considered. Genetic testing for FMF may be useful, particularly in the presence of familial or ethnic predisposition.