Retroperitoneal teratoma in a domestic rabbit (Oryctolagus cuniculus).

Teratomas are histologically complex tumors arising from germ cells of two or three embryonic layers either in the gonads or occasionally from germ cells that mistakenly migrated to ectopic sites. A case of retroperitoneal teratoma in a regularly slaughtered 4-month-old, male domestic rabbit is reported. A pale reddish, 3 x 4 cm, fibrous mass was detected, loosely connected to the parietal wall in the retroperitoneal region cranial to the kidney. Histologically, the neoplasm contained tissues from ectodermal, endodermal and mesodermal germ layers: nerves and neurons simulating ganglia, cysts lined by squamous epithelium containing keratin and hair, skin adnexa; respiratory glandular epithelium, serous and salivary glands; collagenous connective tissue, muscle fibers, mature cartilage and bone, bone marrow, teeth and fat. To the authors' knowledge this is the first report of a retroperitoneal teratoma in the rabbit.