Pulmonary Neoplasms with Pleuropulmonary Blastoma-like Features in Two Young Labrador Retrievers:...

Pleuropulmonary blastoma (PPB) is a rare, paediatric, mesenchymal, pulmonary neoplasm that can be highly aggressive. To date, there are only two reports of PPB in animals. We describe the finding of pulmonary neoplasms with PPB-like features in two unrelated Labrador Retrievers. Both dogs presented with acute dyspnoea, pneumothorax and pulmonary lesions. Treatment consisted of emergency thoracostomy tube placement followed by lung lobectomy. At follow-up, one dog experienced no recurrence 20 months post-surgery, whereas recurrence developed in the second dog 2 years postoperatively. Histopathological examination revealed spindle-shaped neoplastic cells with blastematous-to-sarcomatous appearance, associated with cystic spaces lined by non-neoplastic respiratory epithelium. Immunohistochemistry showed that the neoplastic cells were positive for mesenchymal markers but negative for epithelial and neuroendocrine markers, with some tumour cells showing desmin positivity, supportive of myogenic differentiation, possibly compatible with rhabdomyoblastic differentiation. Genome profiling revealed a heterogeneous somatic landscape. No pathogenic somatic or germline DICER1 variants were found. We compared these findings with those reported in human PPB. This is the first comprehensive analysis of pulmonary neoplasms with PPB-like features in animals, and reveals parallels with PPB in humans, further supporting the 'One Medicine' approach.