Pulmonary parenchymal splenosis

We describe the cytologic findings of a case of pulmonary parenchymal splenosis, a rare condition that follows lacerating trauma to the spleen, and may masquerade as a metastatic neoplasm. Approximately 24 cases of thoracic splenosis have so far been reported, the vast majority presenting as pleural-based nodules, and the cytological features of only two cases, both belonging to the latter group, have been described. We believe our case report to be the first to describe the cytological features of an intrapulmonary splenosis, and its features differ from the prior cases by having a mixed inflammatory cell infiltrate, with a predominance of lymphocytes, plus pulmonary macrophages and occasional endothelial cells. This condition has variable cytological features, but the correct diagnosis can be made in the presence of appropriate history and radiographic findings. Confirmation may require biopsy or radionucleide imaging.