Myxoma of the penis in an African pygmy hedgehog (Atelerix albiventris).

A penile tumor (4 × 2.5 × 1 cm) was surgically removed from an African pygmy hedgehog (Atelerix albiventris) aged 3 years and 5 months. The tumor was continuous with the dorsal fascia of the penile head. Histopathologically, tumor cells were pleomorphic (oval-, short spindle- and star-shaped cells) with low cell density. Abundant edematous stroma was weakly positive for Alcian blue staining and positive for colloidal iron reaction. Tumor cells displayed no cellular atypia or karyokinesis. Tumor cell cytoplasm was positive for vimentin antibody, while cytoplasm and nuclei were positive for S-100 protein antibody. Tumor cell ultrastructure matched that of fibroblasts, and the rough endoplasmic reticulum was enlarged. The tumor was diagnosed as myxoma. This represents the first report of myxoma in a hedgehog.