Prostatic amyloidosis: pathological features of an underdiagnosed condition

Area of Science:

• Urology
• Pathology
• Nephrology

Background:

• Amyloidosis is a rare condition affecting genitourinary organs.
• Prostate involvement is infrequently documented.

Purpose of the Study:

• To review morphologic and immunohistochemical features of prostatic amyloidosis.
• To determine the prevalence and characteristics of amyloid deposition in the prostate.

Main Methods:

• Review of prostate biopsies and surgical specimens.
• Morphologic and immunohistochemical analysis.
• Genetic analysis for amyloid typing.

Main Results:

• Prostatic amyloidosis diagnosed in 25 patients (1.16% of needle biopsies).
• Amyloid deposits primarily in small vessel walls (25 cases) and stroma (3 cases).
• Deposits are most abundant in the prostate periphery and posterolateral regions.
• Immunohistochemistry positive for transthyretin and P amyloid in 24 cases.
• Genetic analysis confirmed transthyretin wild-type amyloidosis in most cases.

Conclusions:

• Prostate amyloidosis is an infrequent finding, characterized by subtle amyloid deposition in small vessel walls.
• It predominantly occurs in the prostate periphery and can be the initial diagnosis for systemic amyloidosis.
• Immunohistochemistry is useful for subtyping, but limitations exist for immunoglobulin light chain amyloidosis.