Oral papillomas and papilliform lesions in rhesus macaques (Macaca mulatta).

Oral papillomas in two male rhesus macaques that were diagnosed morphologically as filiform and squamous types are described. Two additional macaques had oral papilliform lesions consistent histologically with papillary hyperplasia. Immunohistochemistry, along with electron microscopy and PCR assays, failed to demonstrate evidence of papillomavirus in any of the tumors; however, such results are often lacking when suspect oral lesions in humans and other species are assessed. Other potential causes of the papillary masses include chronic irritation and perhaps a genetic susceptibility. Benign tumors of the oral epithelium in macaques have not been reported previously; they appear to be rare and of variable clinical significance.