Keratoacanthoma causing beak deformity in a budgerigar (Melopsittacus undulatus)

This report describes a keratoacanthoma causing abnormal maxillary beak growth in a 6-year-old male budgerigar (Melopsittacus undulates). Although the bird was still capable of eating, it had recently been demonstrating signs of respiratory distress and euthanasia was recommended. On histological examination, the neoplasm was dramatically effacing the normal structure of the maxilla and infiltrating into the rostral nasal sinuses. The tumour consisted of many cyst-like proliferations of well-differentiated squamous epithelial cells with central keratinization. Contiguity of the tumour cells with the stratum germinativum of the beak was noted in one microscopic field. This tumour type has not previously been reported in the avian beak; however, this case shows some similarities to subungual keratoacanthomas occurring in human patients and nailbed keratoacanthomas occurring in dogs and cats.