Pulmonary sarcomas in a young chicken

Both lungs of a 5-wk-old broiler chicken contained miliary, round, white tu mors. Microscopically, these masses were composed of compactly arranged cel ls with round to oval nuclei and indistinct cytoplasmic borders. Immunohist ochemically, tumor cells were positive for vimentin but negative for cytoke ratin, S-100 protein, neuron-specific enolase, smooth muscle actin, and mus cle-specific actin. Ultrastructurally, tumor cells were separated by collag en bands and some contained collagen fibrils. These results suggest that th e primitive mesenchymal cells composing these sarcomas may have originated from precursors of interstitial cells or fibroblasts of the interparabronch ial or interatrial septa. DNA was extracted from paraffin-embedded tissues and probed for sequences s pecific for Marek's disease virus, reticuloendotheliosis viruses, exogenous avian leukosis viruses, and subgroup J avian leukosis viruses. Only sequen ces specific for subgroup J avian leukosis viruses were identified in the D NA extracted from tumors and surrounding lung.