Two renal tumors in cottontail rabbits (Sylvilagus floridanus).

Renal tumors were found in two cottontail rabbits (Sylvilagus floridanus) about 1 year old. One tumor was intimately associated with the kidney and consisted of isolated ductular and tubular structures within an abundant connective tissue stroma and was diagnosed as a hamartoma of urogenital origin. The second was composed of epithelial cells arrange as alveolar structures with papillary projections, epithelium that was less differentiated into tubules and ducts, and neoplastic epithelial cells in solid sheets. The diagnosis of renal adenocarcinoma was based on the histologic features as metastasis had not occurred.