Inverted papilloma with Civatte/colloid body-like eosinophilic structures, accumulated with Keratins 14-, 6a-, 5-, and 4-like proteins in an oriental turtle dove (<i>Streptopelia orientalis</i>)

Cutaneous inverted papilloma is rarely reported in avian species. In this study, an oriental turtle dove presented with subcutaneous masses in the neck, thorax, and leg. Histopathological examination revealed an inverted proliferation of basaloid squamous epithelial cells in a cord-like, lobulated growth pattern containing Civatte/colloid body-like structures, which extend into the abundant stroma with melanosis. Proteomic analysis of formalin-fixed paraffin-embedded tissues identified Keratins 14- and 5-like proteins, with lower levels of Keratins 6A-, and 4-like proteins. Immunohistochemistry confirmed strong reactivity of Keratin 14 in the basal layers of the tumor. This case of cutaneous inverted papilloma was distinguished by unique Civatte/colloid body-like structures and the accumulation of several keratins.