Aim: Primary sarcomatoid carcinoma (PSC) of the lung is a rare malignant neoplasm characterized by the presence of both carcinomatous and sarcomatoid components, typically presenting as a solitary pulmonary mass. Imaging examination serves as a critical tool for the detection and evaluation of pulmonary lesions, the definitive diagnosis of PSC still relies on histopathological examination and immunohistochemical staining results. This study presents a pathologically confirmed case of PSC of the lung with a retrospective analysis of the clinical features and chest computed tomography (CT) imaging findings. The purpose is to improve the diagnostic accuracy of this disease.

Case Presentation: A 67-year-old Chinese male was admitted to the First People's Hospital of Tong Xiang City with a one-week history of cough and expectoration. A plain and contrast-enhanced chest CT scan revealed a large mass in the upper lobe of the right lung, adjacent to the interlobar fissure and parietal pleura. Upon enhancement, the mass demonstrated irregular mild-to-moderate enhancement on the side near the pleura, with no significant enhancement in the central region or near the hilum. A pseudocapsule was observed surrounding the lesion. The patient subsequently underwent resection of the right upper lobe mass. Hematoxylin-eosin staining of the pathological specimen revealed spindle-shaped tumor cells that had invaded the parietal pleura. Immunohistochemical analysis showed positivity for vimentin and cytokeratin, as well as partial positivity for epithelial membrane antigen. Based on these immunohistochemical findings, the tumor was diagnosed as pulmonary sarcomatoid carcinoma (spindle cell type). Approximately 10 months postoperatively, the patient was readmitted due to chest pain and dyspnea lasting four days. The chest CT scan indicated tumor recurrence. The patient was managed conservatively for two months, achieving stable condition before discharge. Two months after discharge, the patient succumbed to complications of concurrent pulmonary infection and cardiopulmonary failure.

Results: Analyzing the pathological findings and CT manifestations in a patient with pulmonary PSC; immunohistochemical staining results can to some extent provide insights into the patient's prognosis.

Conclusions: Owing to the rarity, high-degree malignancy and poor prognosis of PSC, potential cases should be comprehensively evaluated based on imaging, laboratory and pathological results. Long-term regular follow-up is required to rule out the metastasis or recurrence of postoperative pleural metastasis.