A rare case of pulmonary pleomorphic carcinoma presenting as a nearly pure ground-glass nodule on computed tomography: A case report

Pleomorphic carcinoma is a rare subtype of non-small cell cancer, accounting for 0.1 %-0.4 % of all pulmonary malignancies, and is associated with a poor prognosis. Peritumoral ground-glass nodules (GGNs) are commonly observed and have been attributed to various causes, including inflammation, alveolar hemorrhage, and adenocarcinoma. Here, we describe the case of a female patient with a nearly pure GGN in the right upper lobe. Bronchoscopic biopsy confirmed a diagnosis of adenocarcinoma, which was consistent with the low fluorodeoxyglucose uptake observed on imaging. No lymph node involvement or distant metastases were detected, and the patient was subsequently referred for surgical resection. Lobectomy with mediastinal lymph node dissection was performed. Pathological examination of the surgical specimen revealed a lepidic-dominant adenocarcinoma with areas of acinar adenocarcinoma and a small sarcomatoid component, leading to a diagnosis of pleomorphic carcinoma. Immunohistological analysis demonstrated thyroid transcription factor-1 and AE1/AE3 positivity in both the adenocarcinoma and sarcomatoid components, whereas E-cadherin expression was absent in the sarcomatoid component. These findings suggest that the adenocarcinoma underwent epithelial-mesenchymal transition, eventually transforming into a sarcomatoid component. The patient received uracil and tegafur as adjuvant chemotherapy and has survived for 10 years postoperatively without recurrence. Pleomorphic carcinoma presenting as a nearly pure GGN is exceedingly rare, and to the best of our knowledge, this is the first reported case. Our findings provide insights into the role of EMT in pulmonary malignancies.