A case of pulmonary pleomorphic carcinoma with ground-glass opacity surrounding the tumor on CT imaging

Pulmonary pleomorphic carcinoma is a rare subtype of lung cancer, and there have been limited reports on its characteristic features in chest computed tomography (CT) images. Here, we present a case of pulmonary pleomorphic carcinoma in a 73-year-old non-smoking female, which exhibited unique CT imaging with ground-glass opacity (GGO) surrounding the tumor. The patient was initially identified with a 12 mm nodular shadow in the left upper lobe on a chest X-ray during the 2023 community health check-up. Chest thin-section CT imaging showed a GGO above the nodule shadow. No significant lymph node enlargement was observed. The presence of GGO suggested a pathological composition including a lepidic growth pattern of adenocarcinoma. Pathological examination of the resected specimen showed a variety of components, with 70% of the tumor displaying a spindle cell sarcoma-like appearance, and 30% consisting of adenocarcinoma with localized acinar growth and lepidic proliferation at the tumor’s periphery (acinar: lepidic ratio = 2:8). The spindle cell tumor component was weakly positive for AE1/3 immunostaining, positive for vimentin, and exhibited nuclear accumulation of p53. Nuclear accumulation of p53 was also observed in the acinar adenocarcinoma component. Considering the weak positive staining for AE1/3 in the spindle cell tumor component and the similar p53 nuclear accumulation pattern in the surrounding adenocarcinoma, it was speculated that both adenocarcinoma and spindle cell components had a common origin. The final pathological diagnosis was pleomorphic carcinoma (pT1bN0M0). This case suggested a transition from lepidic adenocarcinoma to acinar adenocarcinoma, followed by dedifferentiation of some epithelial components into a more undifferentiated, sarcoma-like component, indicating a continuous spectrum of changes. Driver gene mutation analysis yielded negative results. Programmed cell death 1-ligand 1 (PD-L1) expression was detected with a tumor proportion score (TPS) of 15%. The patient remained well with no recurrence at the 10-month follow-up. Chest CT findings of pulmonary pleomorphic carcinoma typically feature solid nodules or masses, with cases displaying a lepidic adenocarcinoma pattern around the tumor being rare. Herein, we report this case with a brief literature.