Pulmonary artery trunk sarcoma: a clinicopathologic, ultrastructural, and immunohistochemical study of four cases.

Pulmonary artery sarcomas are rare tumors that arise in the region of the bulbus cordis, the embryologic structure that gives rise to the pulmonary trunk. Nearly 100 cases have been reported in the literature, yet considerable debate exists regarding the histogenesis and biologic properties of these neoplasms. We report four additional cases in which ultrastructural and immunohistochemical studies demonstrated that these tumors contain cellular constituents with features of myofibroblastic, cartilaginous, and osteogenic differentiation. Polyphenotypic expression of several mesenchymal lineages suggests that the progenitor cell has pluripotential properties. Our findings and a review of the literature appear to confirm that pulmonary artery sarcomas are histopathologically heterogeneous, possibly reflecting the indeterminate character of the mesenchymal cell(s) of origin. The poor prognosis is attributable to the critical anatomic location of the neoplasm rather than its metastatic potential, which is low.