Cutaneous basaloid squamous cell carcinoma in a captive blue-fronted amazon (Amazona aestiva) in Paraguay: gross description, histological and immunohistochemical findings.

Squamous cell carcinoma (SCC) is a malignant neoplasm that usually arises from the integument, and is reported uncommonly in pet birds. Basaloid SCC is a variant from the prototypic squamous cell carcinoma and is a biologically high grade tumor that shows a sharp predilection for the base of the tongue, the hypopharynx and the supraglottic larynx, manifesting deep and lateral invasion. We present the case of an Amazon aestiva from Paraguay with a basaloid SCC in the skin, of 8 months of evolution. Histologically, the findings were compatible with poorly differentiated carcinoma, and immunohistochemistry resulted positive for cytokeratin AE1/AE3 and 34βe12, and negative for BerEP4, vimentin and CK7, suggesting a basaloid variant of SCC. The owner reported that two weeks after the surgical removal of the mass, the animal was found dead and buried immediately, which is why post-mortem studies could not be carried out. In humans, basaloid SCC is associated with the upper aerodigestive tract but reports distant metastasis, even to the skin, suggesting a primary tumor elsewhere. To the authors best knowledge, this is the first report of basaloid squamous cell carcinoma in a bird.