Abstract

The livers from 35 Micronesian kingfishers necropsied at the National Zoo between 1985 and 2007 were examined histologically with hematoxylin and eosin stain for iron content. Livers with significant pigment clusters were further examined with Perl’s iron, Hall’s bile, lipofuscin and acid-fast stains. Seventeen kingfishers (49%) had significant accumulations of hepatic iron as demonstrated by Perl’s stain. Thirteen of these kingfishers were male and males were identified as having triple the risk of developing hemosiderosis. Affected livers varied in gross appearance. Some livers were enlarged with rounded edges and scattered tan to yellow foci and others were normal to enlarged with diffuse, tan or yellow-orange pallor. The histologic pattern of distribution of iron pigment was consistent from case to case, and the degree of pigmentation varied from moderate to marked in all cases. Throughout the parenchyma, stainable iron was diffuse and granular within hepatocytes and granular to globular within macrophage clusters. Densely staining hemosiderin-laden macrophages were distributed in multifocal, periportal and random clusters, or singly within sinusoids and parenchyma. Minimal stainable iron was also detected in other organs including the heart, renal tubules, lung, spleen, thyroid gland and brain. Ten cases had moderate to marked, multifocal birefringence within pigment clusters. Eleven cases had minimal to moderate portal and periportal, lymphocytic and heterophilic inflammation often surrounding pigment clusters. Two cases had scant to few acid-fast bacilli identified within pigment clusters. A single case had moderate bridging fibrosis and two other cases had marked, diffuse vacuolation of hepatocytes. The cause of death was attributed to liver disease in only one case.