Comparative immunohistochemical characterisation of a teratoma in a domestic duck (Anas platyrhynchos) and a teratocarcinoma in a muscovy duck (Cairina moschata).

Background: Neoplasms consisting of two or more germinal layers are classified as teratomas if benign or as teratocarcinomas if malignant. Teratomas are rare tumours occurring in a wide range of species including mammals, birds and reptiles and only a few cases have been reported in ducks with infrequent documentation of immunohistochemical characterisation. Teratocarcinomas occur rarely and, to the authors' knowledge, have not been described or immunohistochemically characterised in ducks, yet. Therefore, the clinical and pathological presentation of a teratoma in a mulard duck and a teratocarcinoma in a muscovy duck are described. In addition to a histologic examination, both tumours were characterised by applying a panel of immunohistochemical markers previously tested on duck tissue.

Case presentation: A mulard duck (Anas platyrhynchos x Cairina moschata) showed a mass in the cranial coelomic cavity histologically diagnosed as tridermic teratoma. A caudal coelomic mass in a Muscovy duck (Cairina moschata) was histologically diagnosed as a teratocarcinoma with metastases to the liver, mesentery and intestinal wall. An extensive immunohistochemical examination for a detailed characterisation and comparison with duck control tissue was performed in both cases, highlighting various components of the neoplastic tissues including lymphocytes, nervous and endodermal components.

Conclusions: To the authors' knowledge, this is the first report of a teratocarcinoma in a duck with intense immunohistochemical characterisation and comparison with a teratoma in another duck. Immunohistochemistry enables a more profound examination of the histogenetic composition of such neoplasms compared to histology alone. Both neoplasms should be considered as differentials for masses in body cavities of ducks. During these examinations, a large spectrum of antibodies specific for different tissues and cells were tested on duck control tissue which can be of help for immunohistochemical examinations on avian tissues in the future.