[Heterogeneity of seminal vesicle amyloid. Immunohistochemical detection of lactoferrin and amyloid of the prealbumin-transthyretin type].

Localized depositions of amyloid in the seminal vesicles may occur in elderly men. Earlier immunohistochemical studies have failed to identify immunoreactivity of known amyloid material. In this autopsy study, all seminal vesicles of males older than 50 years were histologically examined to determine incidence and phenotype of seminal vesicle amyloidosis. Seven out of 50 patients (14%) showed depositions of amyloid in the seminal vesicles. These amyloid depositions as well as one additional case were characterized histochemically, immunohistochemically and electronmicroscopically. All but two of these patients (75%) showed simultaneously amyloid depositions in the heart. Lactoferrin immunoreactivity was found in 6 patients (75%). Lactoferrin is an iron-binding, bacteriostatic glycoprotein, which is produced in the seminal vesicles. Four patients with lactoferrin positive amyloid in seminal vesicle showed different amyloid depositions in the heart (immunoglobulin light chain amyloid AL-lambda). Two cases (25%) showed the same amyloid type in heart and seminal vesicles (prealbumin-transthyretin type amyloid). Our study shows that most amyloidoses of the seminal vesicles are organ-limited depositions of lactoferrin. These forms of localized amyloidosis have to be separated from senile systemic amyloidosis with seminal vesicle involvement.