Fetiform teratoma in an Italian-Fresian calf: case report and literature review.

Introduction. Fetiform teratoma is a rare form of teratoma in animals and people that resembles a malformed fetus. This paper describes the first case of highly differentiated extragonadal fetiform teratoma with cranial connection in an Italian-Friesian calf. Case presentation. A 35-day-old male Italian-Friesian calf weighing 55 kg was referred because of a mass localized in the fronto-nasal region. The mass contained two lateral structures of similar size and conformation that were recognized as underdeveloped hind limbs, while at its center there was a small tail. The mass was surgically excised and sent to the pathologist for examination. Gross examination identified two femur-like rudimentary limbs and a sketch of bone located in between, morphologically referable to a rudimentary coxae-like bo ne. Some mucinous cysts, a virtual body cavity showing adipose and muscular tissues, some cartilaginous nuclei and a coelomatic body cavity were also noted. Histological examination showed differentiation into skin with dermal appendages, hair, adipose tissue, cartilage, bone, lymphoid tissue, neurovascular bundles, and a rudimentary tail. No neural tissue including spinal cord, brain matter, or gonadal differentiation was seen. On the basis of these findings, the mass was diagnosed as a highly differentiated extragonadal fetiform teratoma. Conclusion. Fetiform teratoma should be included among differential diagnoses in cases of neonatal malformation in bovine. Analyzing the available literature, the Friesian genetic strain seem to be predisposed to fetal malformation, but a systematic reporting of cases is needed, in order to investigate further the epidemiological, etiological, pathophysiological and therapeutic aspect of this kind of congenital disease.