Pulmonary idiopathic alveolar ossification in a raccoon (Procyon lotor)

Abstract

Here we describe gross and histopathologic findings in a laboratory-confined adult male raccoon (Procyon lotor) with microscopic ossified areas in pulmonary alveoli. At the time of necropsy, gross lesions were present in the kidneys and in one thyroid gland. Noteworthy microscopic findings included multifocal foci of osseous tissue within the alveoli of the lungs, bilateral thyroid adenomas, pancreatic islet cell amyloidosis, cortical kidney infarcts, cystic adenomatous hyperplasia of urinary bladder, and mineralizations (psommama bodies) of small blood vessels of meninges and choroid plexus. Pulmonary ossification in raccoons has not been reported previously. The other histopathologic lesions have been documented to occur as incidental findings in raccoons and do not appear to have any apparent association with the formation of osseous foci in the lungs of the animal described.

Figure 1.

Lung of a raccoon with alveolar ossification. Note the distended alveolar spaces and absence of inflammatory cellular infiltrate around the foci of ossification. Hematoxylin and eosin stain; magnification, ×25.

Figure 2.

Lung of a raccoon with alveolar ossification. Higher magnification of section in Figure 1, showing trabecular bone with osteocytes in lacunae in the alveolar spaces. Hematoxylin and eosin stain; magnification, ×400.