Beak keratoacanthomas in two budgerigars (Melopsittacus undulatus) with Knemidocoptes spp. infection

Background Keratoacanthoma is a common cutaneous neoplasia in humans that most often occurs on sun exposed sites and is considered a rapidly growing pseudomalignancy, resembling squamous cell carcinoma. Case description Beak keratoacanthomas were diagnosed in two birds from two different households: in a 10-year-old male and in a 1-year-old male budgerigar (Melopsittacus undulatus). The main clinical findings in both birds were hyperkeratotic lesions on and around the beak caused by Knemidocoptes spp. mites and a mass formation on the side of the lesions. Both masses were solid red, ulcerated, and would bleed easily. Histology results revealed invasive epithelial neoplastic changes with centripetal keratin formation resembling epithelial keratoacanthomas that were formed due to the extensive epithelial damage. Both birds died from profuse hemorrhaging from the well-vascularized tumor. No keratoacanthoma formations were observed in the female cage mates. Conclusions and case relevance In the two cases described in this report keratoacanthomas developed in animals with extensive skin lesions caused by Knemidocoptes spp. infection. Further studies are warranted to confirm the association between these disorders.