Heterotopic kidney tissue in the lung of a free-living common dolphin (Delphinus delphis).

A spontaneous case of renal heterotopia involving the lung parenchyma of a free-living, adult, female common dolphin (Delphinus delphis), which was found stranded alive on the North Adriatic Sea coast of Italy, is reported in this study. The lesion, slightly visible from the macroscopic point of view, had the histologic appearance of a "foreign tissue island," which was poorly demarcated from the surrounding pulmonary tissue. Within such an island, several regularly shaped and apparently mature kidney glomeruli and tubules could be observed, with no evidence of secondary tissue reaction. To the best of our knowledge, this should be the first description of heterotopic kidney tissue occurrence in the lung of any domestic or wild animal species.