Urinary cytopathology in primary bladder amyloidosis

Amyloidosis results from the accumulation of unique extracellular proteins which are not able to be degraded via the usual mechanism of lysosomal proteolysis. Isolated collections of amyloid within the bladder are extremely uncommon, and a cytopathologic description in voided urine has not been described to date.

A retrospective review was performed at a tertiary-care hospital, and 3 patients with isolated bladder amyloidosis and corresponding voided urine specimens were identified. The following clinical data were collected for each case: age, gender, treatment and follow-up information.

The patient age range was 76-84 years, with 2 males and 1 female. Amyloidosis was never clinically suspected. In 1 patient, a urinary amyloid manifested, which was thought to represent extraneous debris at the time of original diagnosis. Two patients never manifested signs of systemic amyloidosis or multiple myeloma, and the third was found to have a monoclonal gammopathy.

Our results show the difficulty of diagnosing urinary amyloid in the absence of clinical suspicion. Further, the presence of urinary amyloid is unlikely in patients with bladder amyloidosis as the cohesive nature of the protein makes spontaneous shedding uncommon. Testing for systemic amyloidosis is warranted and if the disease is localized, a favorable outcome can be expected.