Pleomorphic carcinoma of the lung: A case report with immunohistochemical studies

Because incidence and immunohistochemical features of pulmonary pleomorphic carcinoma (PC) are unclear, the author retrospectively surveyed and re-examined the archival 718 lung malignancy samples in our laboratory. As the results, one case of pulmonary PC was found; thus the incidence of pulmonary PC was 0.14% of all lung malignancies. A 67-year-old woman with asthma was found to have a rapidly growing tumor in the peripheral lower lobe of right lung at a private clinic, and was referred to our hospital. She was a non-smoker. Imaging modalities showed a cystic tumor, and clinical diagnosis was bronchogenic cyst. Right lower lobectomy was performed. The patient is now alive without tumors six years after the operation. Grossly, the tumor was well-defined white tumor with necrosis. The tumor measured 5 × 4 × 5 cm. Histologically, the tumor was pulmonary PC consisting of malignant spindle and giant cells with focal tubular formations. Necrotic foci and numerous mitotic figures were present. Immunohistochemically, tumor cells were positive for pancytokeratin, high molecular weight cytokeratin (CK), CK5/6, CK7, CK14, CK18, CK19, epithelial membrane antigen, vimentin, p53 protein, surfactant apoprotein A, neuron-specific enolase, lysozyme, Ki-67 (60%), and CD68. Tumor cells were negative for CK20, thyroid transcriptional factor-1, CEA, S100 protein, desmin, α-smooth muscle actin, melanosome, CD34, p63, chromogranin, synaptophysin, CD56, KIT, and platelet-derived growth factor-α. It appeared that the present pulmonary PC is associated with adenocarcinoma or derived from sarcomatous transformation of adenocarcinoma.