Metastatic cutaneous neuro- myofibroblastic sarcoma induced by avian leukosis virus subgroup J in a rooster (Gallus gallus domesticus)

An adult native cock (Gallus gallus domesticus) referred to the aviary clinic with multiple different sizes of round dermal nodules. The bird died few days later, and was then submitted for further evaluation. Macroscopic and microscopic examinations as well as a PCR test were done to identify type and cause of the tumor. In histopathological assessment of biopsy specimen, it consisted of interlacing bundles of fibroblasts that orientated in different directions with plump or elongated spindle shaped nuclei and fairly abundant  cytoplasm. At necropsy several large  white nodules were implanted in lung and liver. Microscopically the proliferated fibroblastic cells were invaded to both organs, and were similar to those described for skin lesion. The tumor cells had immunoreaction for alpha smooth muscle actin, vimentin and S100 protein, whereas they were negative for desmin and pancytokeratin, suggesting a diagnosis of metastatic neuro-myofibroblastic sarcoma. A PCR test specific for avian leukosis virus subgroup J (ALV-J) confirmed the presence of that virus in tumor specimens. Sequencing and phylogenetic analysis showed a relatively low similarity in the LTR segment (90%) of the studied virus with other ALV-J strains. It might be the first report of cutaneous neuro-myofibroblastic sarcoma, potentiated to metastasis to other organs  induced by ALV-J.