Amyloidoza pęcherza moczowego — opis przypadku i przegląd piśmiennictwa

Amyloidosis is a heterogeneous group of protein misfolding diseases caused by extracellular deposition of abnormal beta-fibrils resistant to proteolysis. The most common type is light-chain amyloidosis (AL amyloidosis) which can be systemic or localized. Localized amyloidosis mostly affects the respiratory airways, genitourinary tract, gastrointestinal system or skin. We present diagnostic and therapeutic approach in a 25-year-old female patient diagnosed with urinary bladder amyloidosis. The main complaint was macroscopic hematuria occurring periodically for 2 years. Abdominal and pelvic computed tomography revealed single 25-mm-thick soft-tissue lesion of the left bladder wall. Histopathological examination of the lesion biopsied during transurethral resection of bladder tumor showed amyloid deposits with strong positive immunostaining for transthyretin, weaker for light chain (AL) and weak for serum amyloid A (AA). Serum protein electrophoresis and immunofixation did not reveal monoclonal protein. X-rays of flat bones presented without lytic lesions. There were no amyloid deposits both in trephine biopsy and subcutaneous fat biopsy. Primary systemic AL amyloidosis was excluded. According to the results of (99m)Tc-DPD scintigraphy and genetic analysis of transthyretin gene (TTR), the ATTRm amyloidosis was also excluded. Consultative histopathological analysis of the bladder biopsy made in the National Amyloidosis Center in London revealed amyloid deposits stained to lambda light chains, confirming the diagnosis of localized AL lambda bladder amyloidosis. The patient was qualified for surgical treatment. Partial resection of the bladder wall with no need for left ureter transplantation was performed. Primary localized bladder amyloidosis is a very rare entity. In the diagnostic approach the most important is the exclusion of primary systemic amyloidosis due to a completely different treatment method.